Method for producing acrylate derivative, acrylate derivative, and intermediate thereof

ABSTRACT

Provided are 1) a production process for an acrylic ester derivative capable of being a raw material of a polymer for obtaining a photoresist composition capable of forming a photoresist film which is excellent in a reactivity to acid and a heat stability and is less swollen in developing and which has a refractive index of preferably 1.72 or more in 193 nm and can be patterned, 2) an acrylic ester derivative obtained by the above production process and 3) alcohol and ester which are synthetic intermediates for the above acrylic ester derivative.

TECHNICAL FIELD

The present invention relates to a production process for acrylic esterderivatives, acrylic ester derivatives and intermediates thereof. Theacrylic ester derivatives obtained in the present invention are usefulas raw materials for polymers obtained, for example, by polymerizing theabove acrylic ester derivative as one of raw materials and photoresistcompositions obtained by using the above acrylic ester derivative as acomponent. Further, Alcohols and esters obtained in the presentinvention are useful as intermediates for the above acrylic esterderivatives.

BACKGROUND ART

In recent years, electronic devices are highly required to be increasedin integration in the electronic device production field represented byintegrated circuit device production, and this allows aphotolithographic technique for forming fine patterns to be required.Accordingly, photoresist compositions corresponding to photolithographyusing as exposure light, radial rays having a wavelength of 200 nm orless such as an ArF excimer laser (wavelength: 193 nm), an F₂ excimerlaser (wavelength: 157 nm) and the like are actively developed, andproposed are a large number of chemically amplified photoresistcompositions comprising polymer having an acid-dissociable functionalgroup and compounds (herein referred to as “a photoacid generator”)generating acid by irradiation (herein referred to as “exposure”) of aradial ray. The above polymer having an acid-dissociable functionalgroup comprises a basic structure in which a part of an alkali-readilysoluble site of an alkali-soluble polymer is protected by a suitableacid-dissociable functional group, and selection of the aboveacid-dissociable functional group is very important in terms ofcontrolling the performances of the photoresist composition.

Known as the existing acid-dissociable functional group are 1) groupshaving an adamantane structure (refer to a patent document 1 and anon-patent document 1) and 2) groups comprising a tetrahydropyranylgroup (refer to a patent document 2). The acid-dissociable functionalgroup is required to allow a high reactivity to acids to be consistentwith a stability in which it is not decomposed at a baking step andrequested to have a heat stability of 130° C. or higher (refer to anon-patent document 3). The tetrahydropyranyl group in 2) has theadvantage that it has a high reactivity in terms of an aciddissociation, but it is lacking in a heat stability and is notsatisfactory in a fundamental performance of the resist.

One of large problems of lithographic techniques in recent yearsincludes line width variation of formed patterns which is called a linewidth roughness (herein referred to as “LWR”), and an allowable valuethereof is required to be less than 8% of a line width (refer to anon-patent document 3). It is necessary for improving LWR to inhibitpatterns—from being deformed by swelling, that is, to allow a polymerwhich is a photoresist composition component to be less liable to beswollen.

A polymer into which 1) the group having an adamantane structure isintroduced as the acid-dissociable functional group has a highreactivity to acids and a heat stability. However, the above polymer hasa high hydrophobicity and is not satisfactory in an affinity with adeveloper to allow parts which are not dissolved in developing to remainin an exposed area, and it brings about swelling to result in causing aproblem of increasing LWR. Accordingly, polymers for a photoresistcomposition which are less liable to be swollen are still anxious to bedeveloped, and the existing situation is that compounds having anacid-dissociable functional group for achieving the above matter arestrongly anxious to be developed.

Further, finer resist patterns (for example, fine resist patterns havinga line width of about 90 nm) shall be required to be formed in thefuture. In order to achieve formation of resist patterns having a finerline width than 90 nm, it is considered to shift a wavelength of a lightsource in an exposure equipment to a shorter region and increase anumerical aperture (NA) of a lens. However, a new expensive exposureequipment is required for shifting a wavelength of a light source to ashorter region. Further, in an increase in a numerical aperture of alens, a resolution and a depth of focus in a relation of trade-off, andtherefore the problem that the depth of focus is reduced even if theresolution is elevated is involved therein.

In recent years, a method called a liquid immersion lithography isreported as a lithographic technique which makes it possible to solvethe above problem. This method is a method in which purified water or aliquid refractive medium (immersion liquid) such as a fluorinated inertliquid having a prescribed thickness is allowed to be present at leaston a photoresist film between a lens and a photoresist film on asubstrate in exposure. In the above method, even if a light sourcehaving the same exposing wavelength is used, a higher resolving propertyis achieved (provided with a high resolution) as well as having nochange in a depth of focus as is the case with an instance in which alight source having a shorter wavelength is used and an instance inwhich a high NA lens is used by substituting an space of exposureoptical path which has so far been an inert gas such as air and nitrogenwith a liquid having a larger refractive index (n), for example,purified water and the like. Use of the above liquid immersionlithography makes it possible to achieve formation of a resist patternwhich is formed at a lower cost and is excellent in a higher resolvingproperty and which is excellent as well in a depth of focus by using alens mounted in an existing equipment, and therefore it attractsattentions very much.

On the other hand, if a refractive index of a liquid refractive indexmedium (immersion liquid) is higher than a refractive index of, forexample, a photoresist film in a liquid immersion lithographic process,light is less liable to be incident from an immersion liquid into thephotoresist film according to a Snell's law. Accordingly, thefundamental performances such as the sensitivity and the like are likelyto be deteriorated. Further, if an immersion liquid has a highrefractive index, a difference in a refractive index between theimmersion liquid and the photoresist film is increased, and light isreflected wholly on an interface between the immersion liquid and thephotoresist film. Accordingly, since light is not incident completelyinto the photoresist film, the sufficiently high sensitivity is notobtained, and it is anticipated that a throughput in a resist process isnotably reduced.

Then, it is proposed that particularly when an immersion liquid(immersion liquid having a high refractive index) having a refractiveindex of 1.70 or more in a wavelength of 193 nm is used, a photoresistfilm having a higher refractive index than that of the above immersionliquid is used (refer to non-patent documents 4 and 5).

-   Patent document 1: Japanese Patent Application Laid-Open No.    73173/1997-   Patent document 2: Japanese Patent Application Laid-Open No.    88367/1993-   Non-patent document 1: Journal of Photopolymer Science and    Technology, Vol. 9, No. 3, p. 475 to 487 (1996)-   Non-patent document 2: ITRS 2006, UP DATE version, part of    lithography, p. 8-   Non-patent document 3: ITRS 2006, UP DATE version, part of    lithography, p. 7-   Non-patent document 4: SPIE 2006 61530H-   Non-patent document 5: SPIE 2006 61531L

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The photoresist films formed by the materials (photoresist compositions)described in the non-patent documents 4 and 5 have a high refractiveindex in a wavelength of 193 nm, but they can not form resist patternsand are not provided with performances of a photoresist film.Accordingly, photoresist compositions which can form a photoresist filmhaving a high refractive index (for example, a refractive index of 1.72or more) in a wavelength of 193 nm and which provide a photoresist filmcapable of being patterned are anxious to be developed.

In order to solve the problems described above, the present inventionhas been made by paying attentions on an acid-dissociable functionalgroup of a compound having an acid-dissociable functional group andintensely investigating it. The object of the present invention is toprovide 1) a production process for an acrylic ester derivative capableof being a raw material of a polymer for obtaining a photoresistcomposition capable of forming a photoresist film which is excellent ina reactivity to acid and a heat stability and is less swollen indeveloping and which has a refractive index of preferably 1.72 or morein 193 nm and can be patterned, 2) an acrylic ester derivative obtainedby the above production process and 3) alcohol and ester which aresynthetic intermediates for the above acrylic ester derivative.

Means for Solving the Problems

That is, the present invention is achieved by providing:

1. a production process for an acrylic ester derivative (hereinafterreferred to as an acrylic ester derivative (1)) represented by Formula(1) shown below:

(wherein n, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are the same asdefined below), comprising the steps of: reacting dithiol (hereinafterreferred to as dithiol (2)) represented by Formula (2) shown below witha base:

wherein in n, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰,1) when n is 0, R⁵ and R⁸ each represent independently a hydrogen atom,a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl grouphaving 3 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbonatoms; R⁶ and R⁷ each represent independently a hydrogen atom, a linearalkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms orR⁶ and R⁷ are combined to represent an alkylene group having 3 to 6carbon atoms; or2) when n is 1 or 2, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ each representindependently a hydrogen atom, a linear alkyl group having 1 to 6 carbonatoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclicalkyl group having 3 to 6 carbon atoms); then reacting the reactionproduct with halide (hereinafter referred to as halide (4)) representedby Formula (4) shown below:

(wherein combination of R², R³ and R⁴ is any of:1) R², R³ and R⁴ each represent independently a hydrogen atom, a linearalkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms;2) R² and R³ are combined to represent an alkylene group having 3 to 6carbon atoms, and R⁴ represents a hydrogen atom, a linear alkyl grouphaving 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbonatoms or a cyclic alkyl group having 3 to 6 carbon atoms; or3) R² represents a hydrogen atom, a linear alkyl group having 1 to 6carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or acyclic alkyl group having 3 to 6 carbon atoms, and R³ and R⁴ arecombined to represent an alkylene group having 3 to 6 carbon atoms;R¹¹ represents a linear alkyl group having 1 to 3 carbon atoms or abranched alkyl group having 3 to 6 carbon atoms; X represents a chlorineatom, a bromine atom or an iodine atom; and R¹³ represents a linearalkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms) toobtain eater (hereinafter referred to as eater (6)) represented byFormula (6) shown below with a base:

(wherein n, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹³ are the same asdefined above);hydrolyzing the above eater (6) to obtain alcohol (hereinafter referredto as alcohol (5)) represented by Formula (5) shown below:

(wherein n, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are the same asdefined above); andthen reacting the above alcohol with a polymerizable group-introducingagent represented by a formula CH₂═CR¹COX¹ (wherein R¹ is a hydrogenatom, methyl or trifluoromethyl, and X¹ represents a chlorine atom, abromine atom or an iodine atom), a formula (CH₂═CR¹CO)₂O (wherein R¹ isthe same as described above), a formula CH₂═CR¹COOC(═O)R¹⁴ (wherein R¹is the same as described above, and R¹⁴ represents t-butyl or2,4,6-trichlorophenyl) or a formula CH₂═CR¹COOSO₂R¹⁵ (wherein R¹ is thesame as described above, and R¹⁶ represents methyl or p-tolyl) in thepresence of a basic substance,2. the production process for an acrylic ester derivative (1) accordingto the above item 1, wherein the base reacted with the ditiol is sodiumhydride,3. a production process for an acrylic ester derivative (1), comprisingthe steps of:reacting the dithiol (2) with a base;then reacting the reaction product with the halide (4) to obtain thealcohol (5); and thenreacting the above alcohol (5) with a polymerizable group-introducingagent represented by a formula CH₂═CR¹COX¹ (wherein R¹ is the same asdescribed above), a formula (CH₂═CR¹CO)₂O (wherein R¹ is the same asdescribed above), a formula CH₂═CR¹COOC(═O)R¹⁴ (wherein R¹ and R¹⁴ arethe same as described above) or a formula CH₂═CR¹COOSO₂R¹⁵ (wherein R¹and R¹⁵ are the same as described above) in the presence of a basicsubstance,4. the production process for an acrylic ester derivative (1) accordingto the above item 3, wherein the base reacted with the ditiol is sodiumhydride,5. an acrylic ester derivative (1),6. an alcohol (5),7. an ester (6),8. the acrylic ester derivative (1) according to the above item 5,wherein n is 0 or 1, and R³ is a hydrogen atom,9. the acrylic ester derivative (1) according to the above item 5,wherein n is 0 or 1, and R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are ahydrogen atom or methyl,10. the alcohol (5) according to the above item 6, wherein n is 0 or 1,11. the alcohol (5) according to the above item 6, wherein n is 0 or 1,and R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are a hydrogen atom ormethyl,12. the ester (6) according to the above item 7, wherein n is 0 or 1 and13. the ester (6) according to the above item 7, wherein n is 0 or 1,and R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are a hydrogen atom ormethyl.

Effect of the Invention

According to the present invention, capable of being provided are 1) aproduction process for an acrylic ester derivative capable of being araw material of a polymer for obtaining a photoresist compositioncapable of forming a photoresist film which is excellent in a reactivityto acid and a heat stability and is less swollen in developing and whichhas a refractive index of preferably 1.72 or more in 193 nm and can bepatterned, 2) an acrylic ester derivative obtained by the aboveproduction process and 3) alcohol and ester which are syntheticintermediates for the above acrylic ester derivative.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a drawing showing a correlation of an exposure dose of lightradiated on photoresist films formed by photoresist compositions (b) and(d) obtained in Reference Examples 2 and 3 with the film thicknesses ofthe above photoresist films (refer to Reference Examples 18 and 19).

BEST MODE FOR CARRYING OUT THE INVENTION

Acrylic Ester Derivative (1):

R¹ in the acrylic ester derivative (1) represents a hydrogen atom,methyl or trifluoromethyl. R¹ is preferably a hydrogen atom or methyl,more preferably methyl.

Combination of R², R³ and R⁴ in the acrylic ester derivative (1) is anyof 1), 2) and 3) shown below:

1) R², R³ and R⁴ each represent independently a hydrogen atom, a linearalkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms;

2) R² and R³ are combined to represent an alkylene group having 3 to 6carbon atoms, and R⁴ represents a hydrogen atom, a linear alkyl grouphaving 1 to 6 carbon atoms, a branched alkyl group having 3 to 6 carbonatoms or a cyclic alkyl group having 3 to 6 carbon atoms; and3) R² represents a hydrogen atom, a linear alkyl group having 1 to 6carbon atoms, a branched alkyl group having 3 to 6 carbon atoms or acyclic alkyl group having 3 to 6 carbon atoms, and R³ and R⁴ arecombined to represent an alkylene group having 3 to 6 carbon atoms.

The above linear alkyl groups having 1 to 6 carbon atoms include, forexample, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl and thelike in all cases. The above branched alkyl groups having 3 to 6 carbonatoms include, for example, isopropyl, isobutyl, sec-butyl and the likein all cases. The above cyclic alkyl groups having 3 to 6 carbon atomsinclude, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyland the like in all cases.

The alkylene group having 3 to 6 carbon atoms in a case where R² and R³are combined includes, for example, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl and the like. Among them,butane-1,4-diyl is preferred.

The alkylene group having 3 to 6 carbon atoms in a case where R³ and R⁴are combined includes, for example, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl and the like.

The combination of R², R³ and R⁴ is preferably 1) described above, andR², R³ and R⁴ each are more preferably a hydrogen atom or methyl, and R³is particularly preferably a hydrogen atom. All of them are furtherpreferably a hydrogen atom.

In the acrylic ester derivative (1), n, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ areany of 1) and 2) shown below.

1) When n is 0, R⁵ and R⁸ each represent independently a hydrogen atom,a linear alkyl group having 1 to 6 carbon atoms, a branched alkyl grouphaving 3 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbonatoms; R⁶ and R⁷ each represent independently a hydrogen atom, a linearalkyl group having 1 to 6 carbon atoms, a branched alkyl group having 3to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms orR⁶ and R⁷ are combined to represent an alkylene group having 3 to 6carbon atoms.2) When n is 1 or 2, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ each representindependently a hydrogen atom, a linear alkyl group having 1 to 6 carbonatoms, a branched alkyl group having 3 to 6 carbon atoms or a cyclicalkyl group having 3 to 6 carbon atoms.

The above linear alkyl groups having 1 to 6 carbon atoms include, forexample, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl and thelike in all cases. The above branched alkyl groups having 3 to 6 carbonatoms include, for example, isopropyl, isobutyl, sec-butyl and the likein all cases. The above cyclic alkyl groups having 3 to 6 carbon atomsinclude, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyland the like in all cases.

The alkylene group having 3 to 6 carbon atoms in a case where R⁶ and R⁷are combined includes, for example, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl and the like. Among them,butane-1,4-diyl is preferred.

The term n is preferably 0 or 1, more preferably 0.

When n is 0, R⁵, R⁶, R⁷ and R⁰ each are preferably a hydrogen atom ormethyl. More preferably, all of R⁵, R⁶, R⁷ and R⁸ are a hydrogen atom,or both of R⁵ and R⁸ are methyl, and both of R⁶ and R⁷ are a hydrogenatom.

When n is 1, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ each are preferably a hydrogenatom or methyl, and all of R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ are morepreferably a hydrogen atom.

The specific examples of the acrylic ester derivative (1) include, forexample, compounds represented by Formulas (1-a) to (1-x) (wherein n isthe same as defined above, and p represents 1 or 2), but it shall not berestricted to them.

Production Process for Acrylic Ester Derivative (1):

The acrylic ester derivative (1) can be produced, for example, at a stepshown by the following scheme, but it shall not be restricted to thisprocess.

In the scheme described above, n, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ andR¹⁰ are the same as defined above. R¹¹, R¹² and R¹³ each representindependently a linear alkyl group having 1 to 3 carbon atoms or abranched alkyl group having 3 to 6 carbon atoms. X represents a chlorineatom, a bromine atom or an iodine atom.

The above linear alkyl group having 1 to 3 carbon atoms includes methyl,ethyl and n-propyl. The above branched alkyl group having 3 to 6 carbonatoms includes, for example, isopropyl, isobutyl, sec-butyl and thelike. R¹¹, R¹² and R¹³ each are preferably a linear alkyl group having 1to 3 carbon atoms, and they each are more preferably methyl. X ispreferably a chlorine atom or a bromine atom.

In the scheme described above, both the preferred n and the preferredgroups of respective R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹ and R¹⁰ indithiol (2), acetal (3), halide (4) and alcohol (5) are the same as boththe preferred n and the preferred groups of R¹, R², R³, R⁴, R⁵, R⁶, R⁷,R⁸, R⁹ and R¹⁰ in the acrylic ester derivative (1) described above.

The first step to the third step described above shall be explainedbelow in order.

First Step:

In the first step, the halide (4) is synthesized by transacetalation.

The halide (4) can readily be synthesized by reacting acetal(hereinafter referred to as acetal (3)) corresponding to the halide (4)with acid anhydride in the presence of an acid catalyst (refer toTetrahedron, Vol. 50, No. 26, p. 7897 to 7902 (1994)).

Industrially available compounds or compounds produced by subjectingcorresponding α-haloketones or α-haloaldehydes to conventionalacetalization can be used as the acetal (3) used in the first step.

The specific examples of the acetal (3) include, for example,chloroacetaldehyde=dimethyl=acetal, chloroacetaldehyde=diethyl=acetal,bromoacetaldehyde=dimethyl=acetal, bromoacetaldehyde=diethyl=acetal,1-bromo-2,2-dimethoxypropane, 1-iodo-2,2-diethoxypropane,2-bromo-3,3-diethoxybutane, 1-chloro-2,2-dimethoxyhexane,1-chloro-2,2-dimethoxyheptane, 1-chloro-2,2-dimethoxycyclopentane,1-chloro-2,2-dimethoxycyclohexane, 1-bromo-2,2-dimethoxycycloheptahe andthe like, but they shall not specifically be restricted to the abovecompounds.

The acid anhydride used in the first step includes acetic anhydride,propionic anhydride, butanoic anhydride and the like, and aceticanhydride is preferred from the viewpoints of an economical efficiencyand easiness in after-treatment. A use amount of the acid anhydridefalls in a range of preferably 0.5 to 3 moles, more preferably 0.7 to 2moles per mole of the acetal (3) from the viewpoints of an economicalefficiency and easiness in after-treatment.

The first step can be carried out in the presence or the absence of asolvent. The solvent shall not specifically be restricted as long as thereaction is not inhibited, and it includes, for example, aliphatichydrocarbons such as hexane, heptane, octane and the like; aromatichydrocarbons such as toluene, xylene, cymene and the like; halogenatedhydrocarbons such as methylene chloride, dichloroethane and the like;ethers such as tetrahydrofuran (THF), diisopropyl ether and the like.They can be used alone or in a mixture of two or more kinds thereof.Further, the acid anhydride is preferably used in the form of asolvent-cum-reactant from the viewpoint of a reduction in anenvironmental load.

When the solvent is used, a use amount thereof falls in a range ofpreferably 0.1 to 10 mass, more preferably 0.1 to 5 mass per mass of theacetal (3) from the viewpoints of an economical efficiency and easinessin after-treatment.

An acid catalyst is used in the first step. The above acid catalystincludes, for example, carboxylic acids such as acetic acid, propionicacid, benzoic acid and the like; sulfonic acids such asp-toluenesulfonic acid, methanesulfonic acid and the like; mineral acidssuch as sulfuric acid, hydrochloric acid, phosphoric acid and the like.A use amount of the acid catalyst falls in a range of preferably 0.0001to 0.1 mole, more preferably 0.0001 to 0.05 mole per mole of the acetal(3) from the viewpoints of an economical efficiency and easiness inafter-treatment.

A reaction temperature in the first step is varied depending on thekinds of the acetal (3) and the acid catalyst, and it falls in a rangeof preferably 0 to 100° C., more preferably 10 to 70° C.

A pressure in the first step is varied depending on the kinds of theacetal (3), the acid catalyst, the acid anhydride and the solvent, andit can be carried out under either atmospheric pressure or reducedpressure.

The reaction in the first step can be terminated by neutralizing theacid catalyst or removing the acid catalyst from the reaction system.

The neutralizer includes, for example, alkali metal hydroxides such assodium hydroxide, potassium hydroxide and the like; alkali metalcarbonates such as sodium carbonate, potassium carbonate and the like;alkali metal hydrogencarbonates such as sodium hydrogencarbonate,potassium hydrogencarbonate and the like; tertiary amines such astriethylamine, tributylamine and the like; nitrogen-containing alicyclicaromatic hydrocarbons such as pyridine and the like. Among them, thealkaline metal hydrogencarbonates are preferred, and sodiumhydrogencarbonate is more preferred.

When the neutralizer is used, a use amount thereof falls in a range ofpreferably 1 to 3 equivalents based on the acid catalyst from theviewpoints of an economical efficiency and easiness in after-treatment.The solvent described above which can be for the reaction may be addedfor dilution before adding the neutralizer.

A method for terminating the reaction by removing the acid catalyst fromthe reaction system includes, for example, a method in which a reactionsolution under reaction is suitably diluted with a suited reactionsolvent and in which it is then washed with water or an alkaline aqueoussolution. The solvent includes preferably the same ones as the solventsdescribed above which can be used in the reaction of the first step.When the solvent is used for dilution, a use amount thereof falls in arange of preferably 0.1 to 10 mass, more preferably 0.1 to 5 mass permass of a whole mass of the reaction solution from the viewpoints of aneconomical efficiency and easiness in after-treatment.

Also, the basic substance in the alkaline aqueous solution includes, forexample, inorganic bases such as sodium hydroxide, potassium hydroxide,sodium carbonate, sodium hydrogencarbonate, potassium carbonate,potassium hydrogencarbonate and the like. When the alkaline aqueoussolution is used, a use amount of the basic substance falls in a rangeof preferably 0.1 to 3 equivalents based on the acid catalyst from theviewpoints of an economical efficiency and easiness in after-treatment.

The product obtained in the first step can be elevated in a purity byconventional separation/refinement for organic compounds such as solventextraction, distillation, column chromatography, recrystallization andthe like.

Second Step:

The second step comprises a step in which the dithiol (2) is reactedwith the base (hereinafter referred to as a second step-1), a step inwhich the halide (4) is added to the reaction solution obtained in thesecond step-1 to obtain the alcohol (5) (hereinafter referred to as asecond step-2), a step in which the ester (6) by-produced in the secondstep-2 is hydrolyzed if necessary (hereinafter referred to as a secondstep-3) and an after-treating step.

The specific examples of the alcohol (5) obtained in the second stepinclude, for example, alcohols represented by the following formulas,but they shall not specifically be restricted to these compounds.

The second step can be referred to a method described in “GazzetaChimica Italiana, Vol. 127, No. 1, p. 11 to 17 (1997)”. It is describedin the above document that lithium hydride used as the base provides thebest result, but the examples of the base other than it are notdescribed. Use of lithium hydride provides no any problems in a smallamount scale in a laboratory, but problems are involved in anavailability and a handling thereof in an industrial scale, andtherefore the present inventors have investigated the step by usingsodium hydride which can usually be used. As a result thereof, aselectivity of the targeted alcohol (5) is lower when sodium hydride isused than when lithium hydride is used, and they have found that a causethereof is attributable to a larger production amount of the ester (6)as compared with a case where lithium hydride is used. Then, they haveconsidered that if the above ester (6) can be hydrolyzed and convertedinto the targeted alcohol (5), the above method shall be a usefulmethod, and therefore they have intensely investigated the method tofind that the ester (6) can readily be converted into the targetedalcohol (5) by carrying out hydrolysis in an alkaline aqueous solution,and thus they have completed the present invention.

Second Step-1:

The second step-1 is a step in which the dithiol (2) is reacted with thebase to produce a salt of the dithiol (2).

The dithiol (2) used in the second step-1 includes, for example,1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol,2,3-butanedithiol, 2,3-dimethyl-2,3-butanedithiol, 1,2-propanedithiol,2-methyl-1,2-propanedithiol, 2-methyl-2,3-butanedithiol,3,4-hexanedithiol, 2,5-dimethyl-3,4-hexanedithiol, 1,2-butanedithiol,1,2-pentanedithiol, 3,4-octanedithiol, 3,3-dimethyl-1,2-butanedithiol,1,2-cyclopentanedithiol, 1,2-cyclohexanedithiol, 1,3-butanedithiol,2-methyl-1,3-butanedithiol, 2,4-pentanedithiol,2,2-dimethyl-1,3-propanedithiol, 3-methyl-1,3-butanedithiol,2-methyl-2,4-pentanedithiol, 2-ethyl-1,3-propanedithiol,2,4-dimethyl-2,4-pentanedithiol, 2,2-diethyl-1,3-propanedithiol,2,4-hexanedithiol and the like, but they shall not specifically berestricted to the above compounds.

The second step-1 is carried out preferably in the presence of asolvent. The solvent shall not specifically be restricted as long as thereaction is not inhibited, and it includes, for example, dialkyl etherssuch as diethyl ether, tetrahydrofuran, diisopropyl ether, t-butylmethyl ether, cyclopropyl methyl ether and the like; (poly)alkyleneglycol dialkyl ethers such as 1,2-dimethoxyethane, diethylene glycoldimethyl ether, triethylene glycol dimethyl ether and the like; amidessuch as N,N-dimethylformamide and the like. They may be used alone or ina mixture of two or more kinds thereof. Among them, ethers (for example,dialkyl ethers and (poly)alkylene glycol dialkyl ethers) are preferred,and 1,2-dimethoxyethane is more preferred.

A use amount of the solvent falls in a range of preferably 1 to 15 mass,more preferably 3 to 10 mass per mass of the dithiol (2) from theviewpoints of an economical efficiency and easiness in after-treatment.

The base used in the second step-1 may be any of an inorganic base andan organic base. The inorganic base includes, for example, alkali metalhydrides such as sodium hydride, lithium hydride, potassium hydride andthe like; alkali metal hydroxides such as sodium hydroxide, potassiumhydroxide and the like; alkali metal carbonates such as sodiumcarbonate, potassium carbonate and the like. The organic base includes,for example, alkali metal salts of alcohols such as sodium methoxide andthe like; tertiary amines such as triethylamine, N,N-dimethylaniline,tributylamine, diazabicyclo[2.2.2]octane and the like;nitrogen-containing heterocyclic aromatic compounds such as pyridine,4-(N,N-dimethylamino)pyridine and the like. They may be used alone or ina mixture of two or more kinds thereof. Among them, alkali metalhydrides are preferred from the viewpoints of an availability, handling,a reaction yield and an economical efficiency, and sodium hydride ismore preferred. A use amount of the base falls in a range of preferably0.8 to 4 moles, more preferably 1.5 to 2.5 moles based on 1 mole of thedithiol (2) from the viewpoints of an economical efficiency and easinessin after-treatment. If a use amount of the base falls in the rangesdescribed above, a yield of the alcohol (5) in the second step-2 isimproved.

The procedure of the second step-1 shall not specifically be restricted,and when sodium hydride is used as the base, a method in which thedithiol (2) is dropwise added to a solution obtained by suspendingsodium hydride in a suitable solvent is preferred.

A reaction temperature in the second step-1 is varied depending on thekinds of the dithiol (2) and the base, and it falls in a range ofpreferably about 0 to 100° C., more preferably 5 to 70° C. and furtherpreferably 10 to 50° C.

A pressure in the second step-1 is varied depending on the kinds of thedithiol (2), the base and the solvent, and it can be carried out underoptional pressure and is carried out preferably under atmosphericpressure.

A reaction time in the second step-1 falls in a range of preferably 0.1to 5 hours, more preferably 0.1 to 2 hours after finishing addition ofthe dithiol (2). Particularly when sodium hydride is used as the base,the reaction time falls in a range of preferably 0.1 to 3 hours, morepreferably 0.1 to 1.5 hour after finishing addition of the dithiol (2).When sodium hydride is used as the base, hydrogen is generated as thereaction proceeds, but if the reaction time falls in a range of 0.1 to 3hours, hydrogen is terminated to be generated.

Second Step-2:

The second step-2 is carried out by reacting a reaction solutioncontaining a salt of the dithiol (2) obtained in the second step-1 withthe halide (4) obtained in the first step.

The procedure of the second step-2 shall not specifically be restrictedand can be carried out, for example, by a method in which the halide (4)obtained in the first step is dropwise added to a reaction solutioncontaining a salt of the dithiol (2) obtained in the second step-1.

A reaction temperature in the second step-2 is varied depending on thekinds of the dithiol (2), the base and the solvent which are used in thesecond step-1 and the halide (4) obtained in the first step, and itfalls in a range of preferably 0 to 100° C., more preferably 10 to 80°C.

A pressure in the second step-2 is varied depending on the kinds of thedithiol (2), the base and the solvent which are used in the secondstep-1 and the halide (4) obtained in the first step, and it can becarried out at optional pressure and is carried out preferably atatmospheric pressure.

A reaction time in the second step-2 falls in a range of preferably 0.1to 10 hours, more preferably 0.5 to 5 hours after finishing addition ofthe halide (4) obtained in the first step. Particularly when sodiumhydride is used as the base, the reaction time falls in a range ofpreferably 0.1 to 8 hours, more preferably 0.5 to 4 hour after finishingaddition of the halide (4) obtained in the first step. If the reactiontime falls in the above ranges, a conversion of the halide (4) obtainedin the first step is usually 98% or more.

In the second step-2, the ester (6) is by-produced together with thetargeted alcohol (5). The above ester (6) is by-produced in a proportionof the alcohol (5): the ester (6)=10:90 to 70:30 (area ratio) when it isanalyzed by gas chromatography.

Second Step-3:

The second step-3 is a step in which after finishing the reaction in thesecond step-2, the ester (6) by-produced is suitably hydrolyzed toenhance a yield of the targeted alcohol (5). The second step-3 iscarried out by adding water or an alkali aqueous solution to thereaction solution obtained in the second step-2 and stirring themixture.

A number of moles of the base used in the second step-1 exceeds a numberof moles of the halide used in the second step-2 in many cases, andtherefore when water is used in the second step-3, a pH of the solutionto which water is added falls in a range of approximately 10 to 14(alkaline) and shows a range of 11 to 13 in more cases. An amount ofwater added is not only a theoretical amount required for hydrolyzingthe ester (6) by-produced but also, considering an after-treating step,falls in a range of preferably 0.1 to 5 mass, more preferably 0.1 to 1mass per mass of the whole solution in the second step-2.

When an alkali aqueous solution is used, a basic substance contained inthe above alkali aqueous solution is preferably an inorganic salt, andthe inorganic salt includes, for example, alkali metal hydroxides suchas sodium hydroxide, potassium hydroxide and the like; alkali metalcarbonates such as sodium carbonate, potassium carbonate and the like;and alkali metal hydrogencarbonates such as sodium hydrogencarbonate,potassium hydrogencarbonate and the like.

A use amount of the basic substance falls in a range of preferably 0.1to 5 moles, more preferably 0.5 to 3 moles based on 1 mole of the ester(6) from the viewpoints of an economical efficiency and easiness inafter-treatment. A concentration of the alkali aqueous solution shallnot specifically be restricted and can be used in a range of usually0.01 to 20% by mass.

A method in which the alkali aqueous solution or merely the basicsubstance is added, if necessary, after adding water in the secondstep-3 can be employed as well.

The temperature in adding water or the alkali aqueous solution in thesecond step-3 falls in a range of preferably 0 to 100° C., morepreferably 10 to 80° C. and further preferably 20 to 50° C. Thetemperature in the middle of mixing after adding water or the alkaliaqueous solution shall not specifically be restricted and falls in arange of preferably 20 to 100° C., and it is more preferably 50 to 100°C. from the viewpoint of capable of shortening the reaction time.

A pressure in the second step-3 is varied depending on the kinds of thedithiol (2), the base and the solvent which are used in the secondstep-1 and the halide (4) obtained in the first step, and it can becarried out under optional pressure and is carried out preferably underatmospheric pressure.

A reaction time in the second step-3 shall not specifically berestricted, and it is desirable to follow up changes of the alcohol (5)and the ester (6) with the passage of time by gas chromatography and thelike to stop mixing at the point of time when a yield of the alcohol (5)is not elevated. Mixing may be continued over the above point of time,but a yield of the alcohol (5) tends to be gradually reduced. When ayield of the alcohol (5) reaches a maximum point, a ratio of the alcohol(5) to the ester (6) which is analyzed by gas chromatography falls in arange of the alcohol (5): the ester (6)=70:30 to 99:1 (area ratio).

The hydrolysis in the second step-3 can be terminated by neutralizingthe excessive base. The neutralizer includes mineral acids such assulfuric acid, hydrochloric acid, phosphoric acid and the like. Theabove acids diluted to a suitable concentration by water may be used. Atargeted pH thereof in neutralizing falls in a range of preferably 7 to8.

The targeted alcohol (5) contained in the solution after finishing thehydrolysis in the second step-3 can be elevated in a purity byconventional separation/refinement for organic compounds such as solventextraction, distillation, column chromatography, recrystallization andthe like.

Third Step:

The third step is a step in which a polymerizable group is introducedinto the alcohol (5) obtained in the second step.

A method for introducing the polymerizable group into the alcohol (5)shall not specifically be restricted, and it is carried out by reactingthe alcohol (5) with a compound (hereinafter referred to as apolymerizable group-introducing agent) represented by a formulaCH₂═CR¹COX¹, a formula (CH₂═CR¹CO)₂O, a formula CH₂═CR¹COOC(═O)R¹⁴ or aformula CH₂═CR¹COOSO₂R¹⁵ in the presence of a basic substance.

In the polymerizable group-introducing agent described above, all of R¹are the same as R¹ in the acrylic ester derivative (1) described above,and the preferred groups are the same as well. X¹ represents a chlorineatom, a bromine atom or an iodine atom. R¹⁴ represents t-butyl or2,4,6-trichlorophenyl. R¹⁵ represents methyl or p-tolyl.

The specific examples of the polymerizable group-introducing agentrepresented by the formula CH₂═CR¹COX¹ include, for example, acrylicchloride, methacrylic chloride, 2-trifluoromethylacrylic chloride andthe like.

The specific examples of the polymerizable group-introducing agentrepresented by the formula (CH₂═CR¹CO)₂O include, for example, acrylicanhydride, methacrylic anhydride, 2-trifluoromethylacrylic anhydride andthe like.

The specific examples of the polymerizable group-introducing agentrepresented by the formula CH₂═CR¹COOC(═O)R¹⁴ include, for example,acrylic pivalic anhydride, acrylic 2,4,6-trichlorobenzoic anhydride,methacrylic pivalic anhydride, methacrylic 2,4,6-trichlorobenzoicanhydride, 2-trifluoromethylacrylic pivalic anhydride,2-trifluoromethylacrylic 2,4,6-trichlorobenzoic anhydride and the like.

The specific examples of the polymerizable group-introducing agentrepresented by the formula CH₂═CR¹COOSO₂R¹⁵ include, for example,acrylic methanesulfonic anhydride, acrylic p-toluenesulfonic anhydride,methacrylic methanesulfonic anhydride, methacrylic p-toluenesulfonicanhydride, 2-trifluoromethylacrylic methanesulfonic anhydride,2-trifluoromethylacrylic p-toluenesulfonic anhydride and the like.

Among them, the polymerizable group-introducing agents represented bythe formula CH₂═CR¹COX¹ are preferred, and acrylic chloride andmethacrylic chloride are more preferred.

A use amount of the polymerizable group-introducing agent falls in arange of preferably 0.8 to 5 moles, more preferably 0.8 to 3 moles basedon 1 mole of the alcohol (5) from the viewpoints of an economicalefficiency and easiness in after-treatment.

Any of an inorganic base and an organic base can be used for the basicsubstance used in the third step. The inorganic base includes, forexample, alkali metal hydrides such as sodium hydride, potassium hydrideand the like; alkali metal hydroxides such as sodium hydroxide,potassium hydroxide and the like; and alkali metal carbonates such assodium carbonate, potassium carbonate and the like. The organic baseincludes, for example, tertiary amines such as triethylamine,tributylamine, N,N-dimethylaniline, diazabicyclo[2.2.2]octane and thelike; and nitrogen-containing heterocyclic aromatic compounds such aspyridine, 4-(N,N-dimethylamino)pyridine and the like. They may be usedalone or in a mixture of two or more kinds thereof. Among them, thetertiary amines are preferred.

A use amount of the basic substance falls in a range of preferably 0.8to 5 moles, more preferably 0.8 to 3 moles based on 1 mole of thealcohol (5) from the viewpoints of an economical efficiency and easinessin after-treatment.

The third step can be carried out in the presence or the absence of asolvent. The solvent shall not specifically be restricted as long as thereaction is not inhibited, and it includes, for example, ethers such asdiethyl ether, diisopropyl ether, tetrahydrofuran and the like;aliphatic hydrocarbons such as hexane, heptane, octane and the like;halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethaneand the like; aromatic hydrocarbons such as toluene, xylene, cymene andthe like; N,N-dimethylformamide; dimethylsulfoxide and the like. Theymay be used alone or in a mixture of two or more kinds thereof.

When the solvent is used, a use amount thereof shall not specifically berestricted and falls usually in a range of preferably 0.1 to 20 parts bymass, more preferably 0.1 to 10 parts by mass based on 1 part by mass ofthe alcohol (5).

The third step is carried out in a range of preferably −80 to 100° C.,more preferably −50 to 80° C. and further preferably −20 to 40° C. Thereaction time is varied depending on the kinds and the use amounts ofthe alcohol (5) and the polymerizable group-introducing agent, the kindand the use amount of the basic substance, the kind and the use amountof the solvent and the reaction temperature, and it falls usually in arange of 10 minutes to 10 hours.

In the third step, the reaction can be terminated by adding water and/oralcohol. Such alcohol includes, for example, methanol, ethanol,n-propanol, i-propanol and the like.

A use amount of water and/or alcohol is preferably 1 mole or more basedon excess 1 mole of the polymerizable group-introducing agent to thealcohol (5) from the viewpoints of completely decomposing the unreactedpolymerizable group-introducing agent and inhibiting by-products.

The acrylic ester derivative (1) obtained via the above third step ispreferably separated and refined, if necessary, by a conventionalmethod. For example, the reaction mixture is washed with water and thenconcentrated, and a purity thereof can be elevated by a conventionalmethod used for separating and refining organic compounds, such asdistillation, column chromatography or recrystallization.

Further, the acrylic ester derivative (1) obtained can be decreased, ifnecessary, in a metal content by chelate agent treatment bynitrilotriacetic acid, ethylenediaminetetraacetic acid and the like ormetal-removing filter treatment by Zeta Plus (trade name, manufacturedby Cuno K.K.) and Protego (trade name, manufactured by Nihon MicrolisK.K.).

Polymer (8):

A polymer (hereinafter referred to as a polymer (8)) is prepared bypolymerizing a raw material containing at least the acrylic esterderivative (1), and it can be used as a component for a photoresistcomposition.

The polymer prepared by polymerizing the acrylic ester derivative (1) isa polymer prepared by homopolymerizing the acrylic ester derivative (1)or a copolymer prepared by copolymerizing the acrylic ester derivative(1) with other polymerizable compounds, and it has a structural unitbased on the acrylic ester derivative (1). Usually, a content of thestructural unit based on the acrylic ester derivative (1) in the polymer(8) shall not specifically be restricted and falls in a range ofpreferably 10 to 90 mole %, more preferably 20 to 80 mole % from theviewpoints of a solubility to a developer for a photoresist compositiondescribed later, a heat stability and a reduction in LWR. The specificexamples of the structural unit based on the acrylic ester derivative(1) include units represented by the following formulas (1′-a) to(1′-x), but they shall not be restricted to these units.

The specific examples of the other polymerizable compounds (hereinafterreferred to as a copolymerization monomer (7)) which can becopolymerized with the acrylic ester derivative (1) include, forexample, compounds (I) to (IX) represented by the following chemicalformulas:

(wherein R¹⁶ represents a hydrogen atom or an alkyl group having 1 to 3carbon atoms; R¹⁷ represents a polymerizable group; Rn represents ahydrogen atom or —COOR¹⁹, and R¹⁹ represents an alkyl group having 1 to3 carbon atoms; and R²⁰ represents an alkyl group or a cycloalkyl groupin which a carbon atom forming a ring may be substituted with an oxygenatom), but they shall not specifically be restricted to these compounds.

In the copolymerization monomer (7), the alkyl group having 1 to 3carbon atoms each represented independently by R¹⁶ and R¹⁹ includesmethyl, ethyl, n-propyl and isopropyl. The alkyl group represented byR²⁰ includes, for example, alkyl groups having 1 to 8 carbon atoms suchas methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl,t-butyl and the like. The cycloalkyl group represented by R²⁰ in which acarbon atom forming a ring may be substituted with an oxygen atomincludes cyclopentyl, cyclohexyl, 1-methylcyclohexyl, cyclooctyl,tetrahydropyran-2-yl, 4-methyltetrahydropyran-4-yl and the like. Thepolymerizable group represented by R¹⁷ includes, for example, acryloyl,methacryloyl, 2-trifluoromethylacryloyl, vinyl, crotonoyl and the like.

R¹⁶ is preferably a hydrogen atom, methyl, ethyl and isopropyl. R¹⁷ ispreferably acryloyl and methacryloyl. R¹⁸ is preferably a hydrogen atom.R²⁰ is preferably an alkyl group having 1 to 8 carbon atoms.

The other polymerizable compounds which can be copolymerized with theacrylic ester derivative (1) are preferably the compounds (I), (II),(IV), (V), (VI) and (IX), more preferably the compounds (II), (IV) and(VI).

Production Process for the Polymer (8):

The polymer (8) can be produced by radical polymerization according to aconventional method. In particular, living radical polymerization can belisted as a method for synthesizing a polymer having a narrow molecularweight distribution. In a conventional radical polymerization method, atleast one of the acrylic ester derivatives (1) according to necessityand at least one of the copolymerization monomers (7) according tonecessity are polymerized in the presence of a radical initiator, asolvent and, if necessary, a chain transfer agent.

The above radical polymerization method shall be explained below.

A method for carrying out the radical polymerization shall notspecifically be restricted, and conventional methods used in producing,for example, acrylic polymer, such as a solution polymerization method,an emulsion polymerization method, a suspension polymerization method, abulk polymerization method and the like can be used.

The radical initiator includes, for example, hydroperoxides such ast-butyl hydroperoxide, cumene hydroperoxide and the like; dialkylperoxides such as di-t-butyl peroxide, t-butyl-α-cumyl peroxide,di-α-cumyl peroxide and the like; diacyl peroxides such as benzoylperoxide, diisobutyryl peroxide and the like; and azo compounds such as2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutylate and thelike.

A use amount of the radical initiator can suitably be selected accordingto the polymerization conditions such as the kinds and the use amountsof the acrylic ester derivative (1), the copolymerization monomer (7),the chain transfer agent and the solvent which are used for thepolymerization reaction and the polymerization temperature and the like,and it falls usually in a range of preferably 0.005 to 0.2 mole, morepreferably 0.01 to 0.15 mole based on 1 mole of the whole polymerizablecompounds (showing a total amount of the acrylic ester derivative (1)and the copolymerization monomer (7), and hereinafter the same shallapply).

The chain transfer agent includes, for example, thiol compounds such asdodecanethiol, mercaptoethanol, mercaptopropanol, mercaptoacetic acid,mercaptopropionic acid and the like. They may be used alone or in amixture of two or more kinds thereof.

When the chain transfer agent is used, a use amount thereof falls in arange of usually 0.005 to 0.2 mole, preferably 0.01 to 0.15 mole basedon 1 mole of the whole polymerizable compounds.

The radical polymerization is carried out usually in the presence of asolvent. The solvent shall not specifically be restricted as long as thereaction is not inhibited, and it includes, for example, glycol etherssuch as propylene glycol monoethyl ether, propylene glycol monomethylether acetate, ethylene glycol monomethyl ether, ethylene glycolmonomethyl ether acetate, ethylene glycol monomethyl ether propionate,ethylene glycol monobutyl ether, ethylene glycol monobutyl etheracetate, diethylene glycol dimethyl ether and the like; esters such asethyl lactate, methyl 3-methoxypropionate, methyl acetate, ethylacetate, propyl acetate and the like; ketones such as acetone, methylethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methylamyl ketone, cyclopentanone, cyclohexanone and the like; and ethers suchas diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran,1,4-dioxane and the like. They may be used alone or in a mixture of twoor more kinds thereof.

A use amount of the solvent falls in a range of usually 0.5 to 20 partsby mass based on 1 part by mass of the whole polymerizable compounds,and it falls in a range of preferably 1 to 10 parts by mass from theviewpoint of an economical efficiency.

A reaction temperature in the radical polymerization falls usually in arange of preferably 40 to 150° C., and it falls in a range of morepreferably 60 to 120° C. from the viewpoint of a stability of thepolymer (8) produced.

A reaction time in the radical polymerization is varied according to thepolymerization conditions such as the kinds and the use amounts of theacrylic ester derivative (1), the copolymerization monomer (7), thechain transfer agent and the solvent, the polymerization temperature andthe like, and it falls usually in a range of preferably 30 minutes to 48hours, more preferably 1 hour to 24 hours.

The polymer (8) thus obtained can be isolated by an ordinary operationsuch as reprecipitation.

A solvent used in the operation of the reprecipitation described aboveincludes, for example, aliphatic hydrocarbons such as pentane, hexaneand the like; alicyclic hydrocarbons such as cyclohexane and the like;aromatic hydrocarbons such as benzene, xylene and the like; halogenatedhydrocarbons such as methylene chloride, chloroform, chlorobenzene,dichlorobenzene and the like; nitrated hydrocarbons such as nitromethaneand the like; nitriles such as acetonitrile, benzonitrile and the like;ethers such as diethyl ether, diisopropyl ether, tetrahydrofuran,1,4-dioxane and the like; ketones such as acetone, methyl ethyl ketoneand the like; carboxylic acids such as acetic acid and the like; esterssuch as ethyl acetate, butyl acetate and the like; carbonates such asdimethyl carbonate, diethyl carbonate, ethylene carbonate and the like;alcohols such as methanol, ethanol, propanol, isopropanol, butanol andthe like; and water. They may be used alone or in a mixture of two ormore kinds thereof.

A use amount of the solvent is varied depending on the kind of thepolymer (8) and the kind of the solvent, and it falls usually in a rangeof preferably 0.5 to 100 parts by mass based on 1 part by mass of thepolymer (8), and it falls in a range of more preferably 1 to 50 parts bymass from the viewpoint of an economical efficiency.

The polymer thus isolated can be dried by vacuum drying and the like.

The specific examples of the polymer (8) obtained by the methoddescribed above include, for example, polymer represented by thefollowing schemes (8-1) to (8-96) (wherein R²¹ to R³⁵ each representindependently a hydrogen atom, methyl or trifluoromethyl; a, b, c, d ande represent the mole ratios of the repetitive units; a+b is equal to 1,and c+d+e is equal to 1), but they shall not be restricted to thesecompounds.

A weight average molecular weight (Mw) of the polymer (8) shall notspecifically be restricted, and if it falls in a range of preferably 500to 50,000, more preferably 1,000 to 30,000, a usefulness of thecomponent of the photoresist composition described later is high. Theabove weight average molecular weight (Mw) is measured in the mannerdescribed in the example.

Photoresist Composition (9):

A photoresist composition can be prepared by blending the polymer (8)and a solvent, a photoacid generator and, if necessary, a basiccompound, a surfactant and other additives each described later.

The photoresist composition (hereinafter referred to as the photoresistcomposition (9)) blended with the polymer (8) shall be explained below.

Solvent:

The solvent blended with the photoresist composition (9) includes, forexample, glycol ethers such as propylene glycol monoethyl ether,propylene glycol monomethyl ether acetate, ethylene glycol monomethylether, ethylene glycol monomethyl ether acetate, ethylene glycolmonomethyl ether propionate, ethylene glycol monobutyl ether, ethyleneglycol monobutyl ether acetate, diethylene glycol dimethyl ether and thelike; esters such as ethyl lactate, methyl 3-methoxypropionate, methylacetate, ethyl acetate, propyl acetate and the like; ketones such asacetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutylketone, methyl amyl ketone, cyclopentanone, cyclohexanone and the like;and ethers such as diethyl ether, diisopropyl ether, dibutyl ether,tetrahydrofuran, 1,4-dioxane and the like. They may be used alone or ina mixture of two or more kinds thereof.

A blending amount of the solvent falls in a range of usually 1 to 50parts by mass, preferably 2 to 25 parts by mass based on 1 part by massof the polymer (8).

Photoacid Generator:

The photoacid generator shall not specifically be restricted, andphotoacid generators which have so far usually been used for chemicallyamplified resists can be used. The above photoacid generator includes,for example, nitrobenzyl derivatives such as 2-nitrobenzylp-toluenesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate,2,4-dinitrobenzyl p-toluenesulfonate and the like; sulfonic esters suchas 1,2,3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene,1,2,3-tris(p-toluenesulfonyloxy)benzene and the like; diazomethanederivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane,bis(2,4-dimethylphenylsulfonyl)diazomethane,bis(1,1-dimethylethysulfonyl)diazomethane,bis(cyclohexysulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane andthe like; onium salts such as triphenylsulfoniumtrifluoromethanesulfonate, triphenylsulfoniumnonafluoro-n-butanesulfonate, (p-tert-butoxyphenyl)diphenylsulfoniumtrifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfoniumtrifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,(2-norbornyl)methyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate and the like;glyoxime derivatives such as bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime, bis-O-(n-butanesulfonyl)-α-dimethyl glyoxime and the like;sulfonic ester derivatives of N-hydroxyimide compounds such asN-hydroxysuccinimidemethanesulfonic esters,N-hydroxysuccinimidetrifluoromethanesulfonic esters,N-hydroxysuccinimide-1-propanesulfonic esters,N-hydroxyimide-p-toluenesulfonic esters,N-hydroxynaphthalimidemethanesulfonic esters,N-hydroxynaphthalimidebenzenesulfonic esters and the like; andhalogen-containing triazine compounds such as2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,2-(2-(2-furyl)ethenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,2-[2-(5-methyl-2-furyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine,2-[2-(3,5-dimethoxyphenyl)ethenyl)-4,6-bis(trichloromethyl)-1,3,5-triazineand the like. They may be used alone or in a mixture of two or morekinds thereof.

A blending amount of the photoacid generator falls usually in a range ofpreferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts bymass based on 100 parts by mass of the polymer (8) described above fromthe viewpoint of securing a sensitivity and a development of thephotoresist composition (9).

Basic Compound:

The photoresist composition (9) can be blended, if necessary, with abasic compound in an amount of a range in which the characteristics ofthe photoresist composition (9) are not inhibited in order to inhibit adiffusion rate of acid in the photoresist film to enhance a resolutionthereof. The above basic compound includes, for example, amides such asformamide, N-methylformamide, N,N-dimethylformamide, acetamide,N-methylacetamide, N,N-dimethylacetamide, N-(1-adamantyl)acetamide,benzamide, N-acetylethanolamine, acetyl-3-methylpiperidine, pyrrolidone,N-methylpyrrolidone, ε-caprolactam, δ-valerolactam, 2-pyrrolidinone,acrylamide, methacrylamide, t-butylacrylamide, methylenebisacrylamide,methylenebismethacrylamide, N-methylolacrylamide, N-methoxyacrylamide,diacetoneacrylamide and the like; and amines such as pyridine,2-methylpyridine, 4-methylpyridine, nicotine, quinoline, acridine,imidazole, 4-methylimidazole, benzimidazole, pyrazine, pyrazole,pyrrolidine, N-t-butoxycarbonylpyrrolidine, piperidine, tetrazole,morpholine, 4-methylmorpholine, piperazine,1,4-diazabicyclo[2.2.2]octane, tributylamine, tripentylamine,trihexylamine, triheptylamine, trioctylamine, triethanolamine and thelike. They may be used alone or in a mixture of two or more kindsthereof.

When the basic compound is blended, a blending amount thereof is varieddepending on the kind of the basic compound used and falls usually in arange of preferably 0.01 to 10 mole, more preferably 0.05 to 1 molebased on 1 mole of the photoacid generator.

Surfactant:

The photoresist composition (9) can be further blended, if desired, witha surfactant in an amount of a range in which the characteristics of thephotoresist composition (9) are not inhibited in order to enhance thecoating property.

The above surfactant includes, for example, polyoxyethylene laurylether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether,polyoxyethylene n-octylphenyl ether and the like. They may be used aloneor in a mixture of two or more kinds thereof.

When the surfactant is blended, a blending amount thereof is usually 2parts by mass or less based on 100 parts by mass of the polymer (8).

Other Additives:

Further, the photoresist composition (9) can be blended with asensitizer, a halation inhibitor, a form-improving agent, a storagestabilizer, a defoaming agent and the like as other additives in anamount of a range in which the characteristics of the photoresistcomposition (9) are not inhibited.

Formation of Photoresist Pattern:

The photoresist composition (9) is coated on a substrate and pre-bakedusually at 70 to 160° C. for 1 to 10 minutes, and it is irradiated(exposed) with a radiation via a prescribed mask and then subjected topost exposure baking at 70 to 160° C. for 1 to 5 minutes to form alatent image pattern. Then, it is developed in a developer, whereby aprescribed resist pattern can be formed.

Radiations having various wavelengths, for example, a UV ray, an X rayand the like can be used for the exposure, and usually a g beam, an ibeam and excimer lasers of XeCl, KrF, KrCl, ArF, ArCl and the like areused for a semiconductor resist. Among them, an ArF excimer laser ispreferably used from the viewpoint of fine processing.

An exposure dose thereof falls in a range of preferably 0.1 to 1,000mJ/cm², more preferably 1 to 500 mJ/cm².

The developer includes, for example, inorganic bases such as sodiumhydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia andthe like; alkylamines such as ethylamine, diethylamine, triethylamineand the like; alcoholamines such as dimethylethanolamine,triethanolamine and the like; and alkaline aqueous solutions prepared bydissolving quaternary ammonium salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide and the like. Among them,preferably used are the alkaline aqueous solutions prepared bydissolving quaternary ammonium salts such as tetramethylammoniumhydroxide, tetraethylammonium hydroxide and the like.

A concentration of the developer falls usually in a range of preferably0.1 to 20% by mass, more preferably 0.1 to 10% by mass.

Liquid Immersion Lithography:

The photoresist composition (9) can be applied to a liquid immersionlithography. When the photoresist composition (9) is applied to theliquid immersion lithography, purified water or a liquid for liquidimmersion lithography in which a refractive index in a wavelength of 193nm is not smaller than a refractive index of water can be used as animmersion liquid.

The immersion liquid in which a refractive index in a wavelength of 193nm is not smaller than a refractive index of water shall notspecifically be restricted as long as the refractive index in awavelength of 193 nm is not smaller than a refractive index (1.44) ofwater, and various liquids can be used.

When a photoresist film is formed by the photoresist composition (9),the photoresist film having a refractive index of 1.72 or more in awavelength of 193 nm can be obtained. Even when an immersion liquid (animmersion liquid having a high refractive index) having a refractiveindex of 1.70 or more in a wavelength of 193 nm is used in a liquidimmersion lithographic step, the problem that exposure light isreflected wholly on an interface between the immersion liquid and thephotoresist film is less liable to be brought about, and the basicperformances can be prevented from deterioration (for example, areduction in the sensitivity) which originates in whole reflection ofexposure light.

A refractive index of the photoresist film described above is a valuemeasured by irradiating the photoresist film having a thickness of 30 to300 nm with light having a wavelength of 193 nm by means of aspectroscopic ellipsometer (for example, VUV-VASE, manufactured by J. A.Woollam Co., Inc.).

EXAMPLES

The present invention shall be explained in further details withreference to examples, but the present invention shall by no means berestricted by these examples. The measuring methods of Mw and Mn in therespective examples and a calculating method of the dispersion degreeare shown below.

Measurement of Mw and Mn and Calculation of Dispersion Degree:

The weight average molecular weight (Mw) and the number averagemolecular weight (Mn) were measured on the following conditions by gelpermeation chromatography (GPC) using tetrahydrofuran (THF) as an eluantby means of a differential refractometer used as a detector, and theywere determined as values converted by a calibration curve preparedusing standard polystyrene. Further, the dispersion degree (Mw/Mn) wasdetermined by dividing the weight average molecular weight (Mw) by thenumber average molecular weight (Mn).

GPC Measurement:

Used was a column obtained by connecting serially two columns of TSK-gelSUPER HZM-H (trade name, 4.6 mm×150 mm, manufactured by Tosoh Corp.) andone column of TSK-gel SUPER HZ2000 (trade name, 4.6 mm×150 mm,manufactured by Tosoh Corp.), and measurement was carried out on theconditions of a column temperature of 40° C., a differentialrefractometer temperature of 40° C. and a flow velocity of 0.35mL/minute in the eluant.

Synthetic Example 1 Synthesis of 2-chloro-1-methoxyethyl=acetate (FirstStep)

A four neck flask having a content volume of 500 mL equipped with athermometer, a dropping funnel and a stirring device was charged with169.3 g (1.36 mol) of chloroacetaldehyde=dimethyl=acetal and 139.3 g(1.37 mol) of acetic anhydride. The flask was cooled on a water bath,and 0.27 g of conc. sulfuric acid was slowly dropwise added theretowhile stirring. The mixture was stirred at an inside temperature fallingin a range of 20 to 30° C. for 50 hours and then stirred at 50° C. for 3hours while heating. An inside temperature of the reaction solution waslowered down to room temperature, and then it was transferred into aseparating funnel of 1 L. Diisopropyl ether 147.8 g was put thereinto towash the solution twice with 59.0 g of a 7% sodium hydrogencarbonateaqueous solution, and the solvent was removed by distillation underreduced pressure to obtain 221.8 g of a crude for distillation. Amolecular distillation equipment “MS-300” (manufactured by SHIBATASCIENTIFIC TECHNOLOGY LTD.) was used for the distillation. The abovecrude was allowed to flow therethrough at a pressure of 1,330 Pa and atemperature of 30° C. to obtain 188.5 g of a high boiling fraction. Theabove high boiling fraction was allowed to flow therethrough at apressure of 1,330 Pa and a temperature of 40 to 50° C. to obtain 163.5 g(1.01 mol) of 2-chloro-1-methoxyethyl=acetate as a low boiling fractionin the form of a colorless and transparent oil (purity: 94.0%, yield:74%).

Reference Example 1 Case in which Lithium Hydride was Used as a Base inSynthesis of 1,4-dithiane-2-ol (Second Step)

A three neck flask having a content volume of 50 mL equipped with athermometer, a dropping funnel and a stirring device was charged with10.4 g of 1,2-dimethoxyethane, and an inside of the flask wassubstituted with nitrogen. The flask was charged with 108 mg (12.9 mmol)of lithium hydride while cooling it on a water bath, and the mixture wasfor 15 minutes. 1,2-Ethanedithiol 1.13 g (12.0 mmol) was slowly dropwiseadded thereto so that the temperature was maintained in a range of 25 to30° C. In this case, gas was observed to be generated. After stirringfor about 30 minutes since finishing dropwise adding, 974 mg (6.00 mmol)of 2-chloro-1-methoxyethyl=acetate obtained in Synthetic Example 1 wasslowly dropwise added thereto from the dropping funnel so that thetemperature was maintained in a range of 25 to 30° C. After finishingdropwise adding, stirring was continued at 25 to 35° C. for one hour,and the reaction solution was analyzed by gas chromatography. Theresults thereof are shown in Table 1.

Example 1 Case in which Sodium Hydride was Used as a Base in Synthesisof 1,4-dithiane-2-ol (Second Step)

The experiment was carried out in the same manner as in ReferenceExample 1, except that in Reference Example 1, 516 mg (12.9 mmol) ofsodium hydride (60%) was used in place of 108 mg (12.9 mmol) of lithiumhydride. The results thereof are shown in Table 1.

Hydrolysis of 1,4-dithiane-2-yl=acetate

Water 6.8 g was slowly dropwise added to the reaction solution obtainedat a temperature falling in a range of 25 to 40° C. while cooling theflask on a water bath. Immediately after finishing dropwise adding, thepH was confirmed with a pH test paper to find that it was 12. Afterfinishing dropwise adding, stirring was continued while maintaining theinside temperature at 60° C. A change in 1,4-dithiane-2-ol and1,4-dithiane-2-yl=acetate was traced by gas chromatography. The resultsthereof are shown in Table 2.

TABLE 1 comparison of reaction results according to the kind of the basein synthesis of 1,4-dithiane-2-ol Conversion rate of 2-chloro-1-Selectivity (%) methoxyethyl = 1,4-dithiane- 1,4-dithiane- Baseacetate*¹ (%) 2-ol*² 2-yl = acetate*³ Lithium hydride About 100 73.4 8.2Sodium hydride About 100 32.1 65.3 *¹calculated according to (total ofarea of the whole peaks in the compounds produced in the reaction) ÷[(area of a peak of 2-chloro-l-methoxyethyl = acetate) + (total of areaof the whole peaks in the compounds produced in the reaction)] × 100*²calculated according to (area of a peak of 1,4-dithiane-2-ol) ÷ (totalof area of the whole peaks in the compounds produced in the reaction) ×100 *³calculated according to (area of a peak of 1,4-dithiane-2-yl =acetate) ÷ (total of area of the whole peaks in the compounds producedin the reaction) × 100

TABLE 2 results of hydrolysis test of 1,4-dithiane-2- yl = acetateSelectivity (%) Yield of 1,4- Time 1,4-dithiane-2- dithiane-2-ol*³ (hr)1,4-dithiane-2-ol-*¹ yl = acetate*² (% ) 0 32.1 65.3 37.5 5 66.5 20.669.3 8 72.4 13.9 78.0 11 74.3 9.8 77.9 *¹calculated according to (areaof a peak of 1,4-dithiane-2-ol) ÷ (total of area of the whole peaks inthe compounds produced in the reaction) × 100 *²calculated according to(area of a peak of 1,4-dithiane-2-yl = acetate) ÷ (total of area of thewhole peaks in the compounds produced in the reaction) × 100*³calculated according to an internal standard determination methodusing n-decane for an internal standard

It has been found from the results shown in Table 1 that when sodiumhydride is used, a proceeding degree of the reaction is the same as in acase of lithium hydride but a selectivity of targeted 1,4-dithiane-2-olis low and that a cause therefor resides in a large production amount of1,4-dithiane-2-yl=acetate.

Further, it has been found from the results shown in Table 2 that whensodium hydride is used as the base, 1,4-dithiane-2-yl=acetate which isby-produced in a large amount can efficiently be converted into targeted1,4-dithiane-2-ol only by heating and stirring on an alkaline conditionin which water is added to the reaction solution. According to the abovemethod, a method using lithium hydride which is difficult to beindustrially carried out can be avoided.

Example 2 Production of 1,4-dithiane-2-ol (Second Step)

A four neck flask having a content volume of 3 L equipped with athermometer, a dropping funnel and a stirring device was charged with1,390 g of 1,2-dimethoxyethane, and an inside of the flask wassubstituted with nitrogen. The flask was charged with 79.0 g (1.96 mol)of sodium hydride (60%) while cooling it on a water bath, and themixture was stirred for 30 minutes. The flask was equipped with a refluxcondensor, and then 181.2 g (1.92 mol) of 1,2-ethanedithiol was slowlydropwise added thereto from the dropping funnel so that the temperaturewas maintained in a range of 25 to 30° C. In this case, gas was observedto be generated. After stirring for 30 minutes since finishing dropwiseadding, 154.3 g (0.96 mol) of 2-chloro-1-methoxyethyl=acetate obtainedin Synthetic Example 1 was slowly dropwise added thereto from thedropping funnel so that the temperature was maintained in a range of 25to 30° C. After finishing dropwise adding, stirring was continued at 25to 35° C. for 3 hours. In this regard, the reaction solution wasanalyzed by gas chromatography to find that a conversion rate of2-chloro-1-methoxyethyl=acetate was 99.2%.

Hydrolysis of 1,4-dithiane-2-yl=acetate

Water 906.5 g was slowly dropwise added from the dropping funnel at atemperature falling in a range of 25 to 60° C., and after finishingdropwise adding, stirring was continued for 12 hours while maintainingthe temperature at 60° C. by heating the water bath. In this regard, thereaction solution was analyzed by gas chromatography to find that aratio of 1,4-dithiane-2-ol to 1,4-dithiane-2-yl=acetate was1,4-dithiane-2-ol:1,4-dithiane-2-yl=acetate=85:15 (area ratio).

A 10% hydrochloric acid aqueous solution was dropwise added from thedropping funnel at a temperature falling in a of 10 to 15° C. to adjustthe pH to 8.1 (added amount: 112.6 g). The solution obtained wastransferred into a separating funnel having a content volume of 5 L andextracted twice with 1670 g of diisopropyl ether. The extract of twoextractions thus obtained was put into a separating funnel having acontent volume of 5 L and washed in order with 801 g of water and 504 gof a saturated brine, and the solvent was removed by distillation underreduced pressure to obtain 285.9 g of a concentrate. Diisopropyl ether47.5 g, n-hexane 85.2 g and a small amount of a crystal seed were addedto the concentrate thus obtained, and the mixture was slowly cooled downto 0° C. The deposit was separated by filtering and transferred into aflask of 300 mL, and 320 g of n-hexane was added thereto. The mixturewas stirred at 25° C. for 1 hour. The deposit was separated again byfiltering and dried at room temperature under reduced pressure to obtain73.8 g (0.52 mol) of 1,4-dithiane-2-ol showing the following physicalproperties in the form of a white solid (purity: 94.1%, yield: 53%).

¹H-NMR (300 MHz, CDCl₃, TMS, ppm) δ: 2.52 to 2.62 (3H, m), 2.85 (1H, dd,J=2.1, 13.4 Hz), 3.52 to 3.64 (1H, br), 3.86 (1H, ddd, J=5.0, 5.2, 12.1Hz), 4.28 (1H, ddd, J=4.8, 4.9, 12.1 Hz), 5.03 (1H, ddd, J=1.9, 5.8, 7.7Hz).

Example 3 Production of 1,4-dithiane-2-yl=methacrylate (Third Step)

A four neck flask having a content volume of 1 L equipped with athermometer, a dropping funnel and a stirring device was charged with34.5 g (238 mmol) of 1,4-dithiane-2-ol obtained in Example 2, 349.3 g ofTHF and 0.47 g of phenothiazine, and an inside of the flask wassubstituted with nitrogen. Triethylamine 48.2 g (476 mmol) was dropwiseadded thereto from the dropping funnel so that the temperature wasmaintained in a range of 5 to 8° C. in a state in which the flask wascooled on an ice bath.

Next, 30.4 g (287.9 mmol) of methacrylic chloride was dropwise addedthereto so that the temperature was maintained in a range of 5 to 10° C.After finishing dropwise adding, stirring was continued at 3 to 6° C.for 2.5 hours. In this regard, the reaction solution was analyzed by gaschromatography to find that a conversion rate of 1,4-dithiane-2-ol was99.6%.

Water 233 g was slowly dropwise added from the dropping funnel so thatthe temperature was maintained at lower than 20° C., and after finishingdropwise adding, the ice bath was removed to leave the insidetemperature to 24° C. 4-Dimethylaminopyridine 1.46 g was added thereto,and the mixture was stirred at 24 to 26° C. for 2 hours. In this regard,the reaction solution was analyzed by gas chromatography to find that aratio of methacrylic anhydride to 1,4-dithiane-2-yl=methacrylate wasmethacrylic anhydride: 1,4-dithiane-2-yl=methacrylate=0.1:99.9 (arearatio).

The solution obtained was transferred into a separating funnel having acontent volume of 2 L and extracted three times with 240 g of ethylacetate. The extract of three extractions thus obtained was put into aseparating funnel having a content volume of 2 L and washed in orderwith three times 230 g of a 1% hydrochloric acid aqueous solution, 116 gof water, 118 g of a saturated sodium hydrogencarbonate aqueoussolution, twice 118 g of water and 100 g of a saturated brine.p-Methoxyphenol 0.010 g and phenothiazine 0.020 g were added thereto,and the solvent was removed by distillation under reduced pressure toobtain 55.0 g of a crude for distillation. A molecular distillationequipment “MS-300” (manufactured by SHIBATA SCIENTIFIC TECHNOLOGY LTD.)was used for the distillation. The above crude was allowed to flowtherethrough at a pressure of 13.3 to 20.0 Pa and a temperature of 40 to45° C. to obtain 47.4 g of a high boiling fraction. The above highboiling fraction was allowed to flow therethrough at a pressure of 10.7to 13.3 Pa and a temperature of 55 to 60° C. to obtain 37.8 g (182 mmol)of 1,4-dithiane-2-yl=methacrylate showing the following physicalproperties as a low boiling fraction in the form of a colorless andtransparent oil (purity: 98.4%, yield: 76%).

Also, log P which is a log value of an octanol/water distributioncoefficient and SP which is a solubility parameter were calculated byusing Hamiltonian PM5 of a calculation soft “CAChe” (trade name,manufactured by Fujitsu Limited).

¹H-NMR (300 MHz, CDCl₃, TMS, ppm) δ: 2.00 (3H, s), 2.68 to 2.82 (2H, m),2.94 (1H, dd, J=5.2, 14.1 Hz), 3.10 (1H, ddd, J=2.2, 13.2 Hz), 3.30 to3.41 (2H, m), 5.67 (1H, s), 5.87 to 5.92 (1H, m), 6.28 (1H, s)

log P: 1.77

SP: 17.6 (J/mol)^(0.5)

Example 4 Production of 1,4-dithiepane-2-ol (Second Step)

A four neck flask of 3 L equipped with a thermometer, a dropping funneland a stirring device was charged with 1390 g of 1,2-dimethoxyethane,and an inside of the flask was substituted with nitrogen. The flask wascharged with 79.0 g (1.96 mol) of sodium hydride (60%) while cooling iton a water bath, and the mixture was stirred for 30 minutes. The flaskwas equipped with a reflux condensor, and then 209.9 g (1.92 mol) of1,3-propanedithiol was slowly dropwise added thereto from the droppingfunnel so that the temperature was maintained in a range of 25 to 30° C.In this case, gas was observed to be generated. After stirring for 30minutes since finishing dropwise adding, 154.3 g (0.96 mol) of2-chloro-1-methoxyethyl=acetate obtained in Synthetic Example 1 wasslowly dropwise added thereto from the dropping funnel so that thetemperature was maintained in a range of 25 to 30° C. After finishingdropwise adding, stirring was continued at 25 to 35° C. for 5 hours. Inthis regard, the reaction solution was analyzed by gas chromatography tofind that a conversion rate of 2-chloro-1-methoxyethyl=acetate was98.9%.

Hydrolysis of 1,4-dithiepane-2-yl=acetate

Water 906.0 g was slowly dropwise added from the dropping funnel at atemperature falling in a range of 25 to 60° C., and after finishingdropwise adding, stirring was continued for 12 hours while maintainingthe temperature at 60° C. by heating the water bath. In this regard, thereaction solution was analyzed by gas chromatography to find that aratio of 1,4-dithiepane-2-ol to 1,4-dithiepane-2-yl=acetate was1,4-dithiepane-2-ol 1,4-dithiepane-2-yl=acetate=82:18 (area ratio).

A 10% hydrochloric acid aqueous solution was dropwise added from thedropping funnel at a temperature falling in a range of 10 to 15° C. toadjust the pH to 6.2. The solution obtained was transferred into aseparating funnel having a content volume of 5 L and extracted twicewith 1650 g of diisopropyl ether. The extract of two extractions thusobtained was put into a separating funnel having a content volume of 5 Land washed in order with 800 g of water and 500 g of a saturated brine,and the solvent was removed by distillation under reduced pressure. Theconcentrate was refined by silica gel chromatography to thereby obtain40.8 g (0.26 mol) of 1,4-dithiepane-2-ol (purity: 97.1%, yield: 27.5%).

Example 5 Production of 1,4-dithiepane-2-yl=methacrylate (Third Step)

A four neck flask having a content volume of 100 ml equipped with athermometer, a dropping funnel and a stirring device was charged with3.68 g (23.8 mmol) of 1,4-dithiepane-2-ol obtained in Example 4, 34.9 gof THF and 47 mg of phenothiazine, and an inside of the flask wassubstituted with nitrogen. Triethylamine 4.82 g (47.6 mmol) was dropwiseadded thereto from the dropping funnel so that the temperature wasmaintained in a range of 5 to 8° C. in a state in which the flask wascooled on an ice bath.

Next, 3.04 g (28.8 mmol) of methacrylic chloride was dropwise addedthereto so that the temperature was maintained in a range of 5 to 10° C.After finishing dropwise adding, stirring was continued at 3 to 7° C.for 3 hours. In this regard, the reaction solution was analyzed by gaschromatography to find that a conversion rate of 1,4-dithiepane-2-ol was99.2%.

Water 23.3 g was slowly dropwise added from the dropping funnel so thatthe temperature was maintained at lower than 20° C., and after finishingdropwise adding, the ice bath was removed to leave the insidetemperature to 24° C. 4-Dimethylaminopyridine 0.15 g was added thereto,and the mixture was stirred at 23 to 26° C. for 2 hours. In this regard,the reaction solution was analyzed by gas chromatography to find that aratio of methacrylic anhydride to 1,4-dithiepane-2-yl=methacrylate wasmethacrylic anhydride: 1,4-dithiepane-2-yl=methacrylate=0.1:99.9 (arearatio). The solution obtained was transferred into a separating funnelhaving a content volume of 200 mL and extracted three times with 25 g ofethyl acetate. The extract of three extractions thus obtained was putinto a separating funnel having a content volume of 200 mL and washed inorder with three times 23 g of a 1% hydrochloric acid aqueous solution,15 g of water, 15 g of a saturated sodium hydrogencarbonate aqueoussolution, twice 15 g of water and 10 g of a saturated brine.p-Methoxyphenol 2.0 mg and phenothiazine 2.0 mg were added thereto, andthe solvent was removed by distillation under reduced pressure. Theconcentrate was refined by silica gel chromatography to thereby obtain4.36 g (19.5 mmol) of 1,4-dithiepane-2-yl=methacrylate (purity: 97.7%,yield: 81.9%).

Example 6 Production of 5,6-dimethyl-1,4-dithiane-2-ol (Second Step)

A four neck flask of 300 mL equipped with a thermometer, a droppingfunnel and a stirring device was charged with 139 g of1,2-dimethoxyethane, and an inside of the flask was substituted withnitrogen. The flask was charged with 7.90 g (197 mmol) of sodium hydride(60%) while cooling it on a water bath, and the mixture was stirred for30 minutes. The flask was equipped with a reflux condensor, and then24.2 g (192 mmol) of 2,3-butanedithiol was slowly dropwise added theretofrom the dropping funnel so that the temperature was maintained in arange of 25 to 30° C. In this case, gas was observed to be generated.After stirring for 30 minutes since finishing dropwise adding, 15.4 g(94.9 mmol) of 2-chloro-1-methoxyethyl=acetate obtained in SyntheticExample 1 was slowly dropwise added thereto from the dropping funnel sothat the temperature was maintained in a range of 25 to 30° C. Afterfinishing dropwise adding, stirring was continued at 25 to 30° C. for 5hours. In this regard, the reaction solution was analyzed by gaschromatography to find that a conversion rate of2-chloro-1-methoxyethyl=acetate was 98.8%.

Hydrolysis of 5,6-dimethyl-1,4-dithiane-2-yl=acetate

Water 90.0 g was slowly dropwise added from the dropping funnel at atemperature falling in a range of 25 to 60° C., and after finishingdropwise adding, stirring was continued for 12 hours while maintainingthe temperature at 60° C. by heating the water bath. In this regard, thereaction solution was analyzed by gas chromatography to find that aratio of 5,6-dimethyl-1,4-dithiane-2-ol to5,6-dimethyl-1,4-dithiane-2-yl=acetate was5,6-dimethyl-1,4-dithiane-2-ol:5,6-dimethyl-1,4-dithiane-2-yl=acetate=88:12 (area ratio).

A 10% hydrochloric acid aqueous solution was dropwise added from thedropping funnel at a temperature falling in a range of 10 to 15° C. toadjust the pH to 8.2. The solution obtained was transferred into aseparating funnel having a content volume of 500 ml, and extracted twicewith 160 g of diisopropyl ether. The extract of two extractions thusobtained was put into a separating funnel having a content volume of 500mL and washed in order with 10 g of water and 20 g of a saturated brine,and the solvent was removed by distillation under reduced pressure. Theconcentrate was refined by silica gel chromatography to thereby obtain9.09 g (54.1 mmol) of 5,6-dimethyl-1,4-dithiane-2-ol (purity: 97.8%,yield: 57.0%).

Example 7 Production of 5,6-dimethyl-1,4-dithiane-2-yl=methacrylate(Third Step)

A four neck flask having a content volume of 100 mL equipped with athermometer, a dropping funnel and a stirring device was charged with4.00 g (23.8 mmol) of 5,6-dimethyl-1,4-dithiane-2-ol obtained in Example6, 34.9 g of THF and 47 mg of phenothiazine, and an inside of the flaskwas substituted with nitrogen. Triethylamine 4.82 g (47.6 mmol) wasdropwise added thereto from the dropping funnel so that the temperaturewas maintained in a range of 5 to 8° C. in a state in which the flaskwas cooled on an ice bath.

Next, 3.04 g (28.8 mmol) of methacrylic chloride was dropwise addedthereto so that the temperature was maintained in a range of 5 to 10° C.After finishing dropwise adding, stirring was continued at 3 to 7° C.for 3 hours. In this regard, the reaction solution was analyzed by gaschromatography to find that a conversion rate of5,6-dimethyl-1,4-dithiane-2-ol was 99.0%.

Water 23.3 g was slowly dropwise added from the dropping funnel so thatthe temperature was maintained at lower than 20° C., and after finishingdropwise adding, the ice bath was removed to leave the insidetemperature to 24° C. 4-Dimethylaminopyridine 0.15 g was added thereto,and the mixture was stirred at 23 to 26° C. for 2 hours. In this regard,the reaction solution was analyzed by gas chromatography to find that aratio of methacrylic anhydride to5,6-dimethyl-1,4-dithiane-2-yl=methacrylate was methacrylic anhydride:5,6-dimethyl-1,4-dithiane-2-yl=methacrylate=0.1:99.9 (area ratio).

The solution obtained was transferred into a separating funnel having acontent volume of 200 mL and extracted three times with 25 g of ethylacetate. The extract of three extractions thus obtained was put into aseparating funnel having a content volume of 200 mL and washed in orderwith three times 23 g of a 1% hydrochloric acid aqueous solution, 15 gof water, 15 g of a saturated sodium hydrogencarbonate aqueous solution,twice 15 g of water and 10 g of a saturated brine. p-Methoxyphenol 2.0mg and phenothiazine 2.0 mg were added thereto, and the solvent wasremoved by distillation under reduced pressure. The concentrate wasrefined by silica gel chromatography to thereby obtain 4.85 g (20.3mmol) of 5,6-dimethyl-1,4-dithiane-2-yl=methacrylate (purity: 97.2%,yield: 85.3%).

Example 8 Evaluation of a Reactivity of the Acrylic Ester Derivative (1)to Acid

An NMR tube was charged with 2.73×10⁻⁴ mol of1,4-dithiane-2-yl=methacrylate obtained in Example 3, 0.69 mL of1,1,2,2-tetrachloroethane-d₂ and 1.47×10⁻⁶ mol of methanesulfonic acid,and it was provided with a cap and shaken up well.

The above NMR tube was dipped in an oil bath of 120° C. for severalseconds to several minutes, and then the NMR tube was taken out and putin an ice bath to cool the reaction solution. Then, ¹H-NMR thereof wasimmediately measured by means of “NMR Gemini-300” (trade name,manufactured by Varian Technologies Limited). Unreacted methacrylicester and acrylic acid produced by the reaction were observed in the NMRchart of methacrylic ester reacted, and a conversion rate in thedissociation reaction was determined from the respective vinyl protons.Thereafter, an operation in which the above NMR tube was dipped in theoil bath of 120° C. for several seconds to several minutes and cooled inthe ice bath to measure the ¹H-NMR was repeated several times todetermine the conversion rates to the reaction time in several points.The conversion rates versus the reaction time determined above wereplotted on an X axis of the time (s) and a Y axis of ln(1−X) accordingto the following primary reaction rate equation−kt=ln(1−X)  (Equation 1)(wherein k represents a rate constant (s⁻¹); t represents time (s); andX represents a conversion rate), and a rate constant in deprotectionreaction of methacrylic ester at 120° C. was determined from a gradientof the straight line.

2-Methacryloyloxy-2-methyladamantane which was usually used was selectedas a comparative object to determine the rate constant at 120° C. by thesame method as in 1,4-dithiane-2-yl=methacrylate. A relative activity of1,4-dithiane-2-yl=methacrylate to 2-methacryloyloxy-methyladamantane wasdetermined by dividing a rate constant in deprotection reaction of1,4-dithiane-2-yl=methacrylate by a rate constant in deprotectionreaction of 2-methacryloyloxy-2-methyladamantane, and it was set to anindex of the reactivity (activity in deprotection reaction) to acid.

The operation and the analysis described above were carried out at 140°C. The results thereof are shown in Table 3.

Example 9 Evaluation of a Reactivity of the Acrylic Ester Derivative (1)to Acid

The experiment was carried out in the same manner as in Example 8,except that in Example 8, 1,4-dithiepane-2-yl=methacrylate obtained inExample 5 was used in place of 1,4-dithiane-2-yl=methacrylate, and thereactivity (activity in deprotection reaction) to acid was evaluated bythe same method. The results thereof are shown in Table 3.

Example 10 Evaluation of a Reactivity of the Acrylic Ester Derivative(1) to Acid

The experiment was carried out in the same manner as in Example 8,except that in Example 8, 5,6-dimethyl-1,4-dithiane-2-yl=methacrylateobtained in Example 7 was used in place of1,4-dithiane-2-yl=methacrylate, and the reactivity (activity indeprotection reaction) to avid was evaluated by the same method. Theresults thereof are shown in Table 3.

TABLE 3 relative activity in deprotection reaction in the presence ofmethanesulfonic acid Example Acrylic 8 9 10 ester 1,4-dithiane-1,4-dithiepane- 5,6-dimethyl- derivative 2-methacryloyloxy- 2-yl = 2-y1= 1,4-dithiane-2- (1) 2-methyladamantane methacrylate methacrylate yl =methacrylate Relative 1.00 6.95 4.23 6.02 activity (120° C.) Relative1.00 4.12 3.22 3.99 activity (140° C.)

Examples 11 to 13 Activation Energy in Deprotection Reaction of theAcrylic Ester Derivative (1)

The rate constants in the deprotection reaction at 120° C. and 140° C.which were determined by analysis in Examples 8 to 10 were substitutedfor the following equation (Equation 2) to determine the activationenergy (E) in the deprotection reaction of the respective acrylic esterderivatives (1). The results thereof are shown in Table 4.

$\begin{matrix}{{\log\frac{k_{2}}{k_{1}}} = {\frac{E}{2.303\; R}\left( {\frac{1}{T_{1}} - \frac{1}{T_{2}}} \right)}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$(wherein k₁ represents a rate constant (s⁻¹) in the deprotectionreaction at 120° C.; k₂ represents a rate constant (s⁻¹) in thedeprotection reaction at 140° C.; E represents an activation energy(kcal/mol) in the deprotection reaction; R represents an air constant(1.987 cal·K⁻¹·mol⁻¹; T₁ represents an absolute temperature (K) of 120°C.; T₂ represents an absolute temperature (K) of 140° C.).

TABLE 4 activation energy in deprotection reaction Example Acrylic 11 1213 ester 1,4-dithiane- 1,4-dithiepane- 5,6-dimethyl- derivative2-methacryloyloxy- 2-yl = 2-yl = 1,4-dithiane-2- (1) 2-methyladamantanemethacrylate methacrylate yl = methacrylate Activation 18.8 10.3 14.412.1 energy (kcal/mol)

It has been found from the results shown in Tables 3 and 4 that whencompared with publicly known methacrylic esters, the acrylic esterderivatives (1) of the present invention have a high reactivity to acids(refer to Examples 8 to 11) and that they have a low activation energy(refer to Examples 11 to 13), and therefore they are useful as rawmaterials for chemically amplified resists.

Synthetic Example 2 Synthesis of Polymer (a)

A round-bottom flask having a content volume of 50 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 1.00 g (4.89 mmol) of 1,4-dithiane-2-yl=methacrylateobtained in Example 3, 4.00 g of 1,4-dioxane and 99.7 mg (0.401 mmol) of2,2′-azobis(2,4-dimethylvaleronitrile) under nitrogen atmosphere tocarry out polymerization reaction at 60° C. for 3 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering andwashed with methanol of the same mass as described above, whereby awhite precipitate was obtained. The above precipitate was dried at 50°C. for 10 hours under reduced pressure (26.7 Pa) to obtain 0.56 g of apolymer (a) comprising a repetitive unit shown below. The polymer (a)thus obtained had Mw of 23,800 and a dispersion degree of 2.90.

Synthetic Example 3 Synthesis of Polymer (b)

A round-bottom flask having a content volume of 200 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 8.16 g (39.1 mmol) of 1,4-dithiane-2-yl=methacrylateobtained in Example 3, 9.25 g (39.1 mmol) of3-hydroxy-1-adamantyl=methacrylate, 168.0 g of 1,4-dioxane and 1.95 g(7.86 mmol) of 2,2′-azobis(2,4-dimethylvaleronitrile) under nitrogenatmosphere to carry out polymerization reaction at 60 to 65° C. for 4hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 150.0 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain10.3 g of a polymer (b) comprising a repetitive unit shown below. Thepolymer (b) thus obtained had Mw of 13,600 and a dispersion degree of1.50.

Synthetic Example 4 Synthesis of Polymer (c)

A round-bottom flask having a content volume of 200 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 8.00 g (38.4 mmol) of 1,4-dithiane-2-yl=methacrylateobtained in Example 3, 8.53 g (38.4 mmol) of5-methacryloyloxy-2,6-norbornanecarbolactone, 130.0 g of 1,4-dioxane and3.89 g (15.7 mmol) of 2,2′-azobis(2,4-dimethylvaleronitrile) undernitrogen atmosphere to carry out polymerization reaction at 60 to 65° C.for 3 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 80.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 12.1 g of a polymer (c) comprising a repetitive unit shown below.The polymer (c) thus obtained had Mw of 10,600 and a dispersion degreeof 1.83.

Synthetic Example 5 Synthesis of Polymer (d)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Synthetic Example 4, except that in SyntheticExample 4, 6.53 g (38.4 mmol) of α-methacryloyloxy-γ-butyrolactone wasused in place of 8.53 g (38.4 mmol) of5-methacryloyloxy-2,6-norbornanecarbolactone and that a use amount of2,2′-azobis(2,4-dimethylvaleronitrile) was changed from 3.89 g (15.7mmol) to 1.95 g (7.83 mmol).

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 80.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 9.4 g of a polymer (d) comprising a repetitive unit shown below.The polymer (d) thus obtained had Mw of 8,600 and a dispersion degree of1.67.

Synthetic Example 6 Synthesis of Polymer (e)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Synthetic Example 5, except that in SyntheticExample 5, a use amount of α-methacryloyloxy-γ-butyrolactone was changedfrom 6.53 g (38.4 mmol) to 4.36 g (25.6 mmol) and that a use amount of2,2′-azobis(2,4-dimethylvaleronitrile) was changed from 1.95 g (7.83mmol) to 1.64 g (6.62 mmol).

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 80.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 10.2 g of a polymer (e) comprising a repetitive unit shown below.The polymer (e) thus obtained had Mw of 9,900 and a dispersion degree of1.75.

Synthetic Example 7 Synthesis of Polymer (f)

A round-bottom flask having a content volume of 100 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 3.88 g (18.7 mmol) of 1,4-dithiane-2-yl=methacrylateobtained in Example 3, 2.95 g (12.5 mmol) of3-hydroxy-1-adamantyl=methacrylate, 4.16 g (18.7 mmol) of5-methacryloyloxy-2,6-norbornanecarbolactone, 100.0 g of 1,4-dioxane and2.48 g (10.0 mmol) of 2,2′-azobis(2,4-dimethylvaleronitrile) undernitrogen atmosphere to carry out polymerization reaction at 60 to 65° C.for 4 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 80.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 6.5 g of a polymer (f) comprising a repetitive unit shown below.The polymer (f) thus obtained had Mw of 12,800 and a dispersion degreeof 1.82.

Synthetic Example 8 Synthesis of Polymer (g)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Synthetic Example 7, except that in SyntheticExample 7, 3.18 g (18.7 mmol) of α-methacryloyloxy-γ-butyrolactone wasused in place of 4.16 g (18.7 mmol) of5-methacryloyloxy-2,6-norbornanecarbolactone.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 80.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 5.61 g of a polymer (g) comprising a repetitive unit shown below.The polymer (g) thus obtained had Mw of 11,900 and a dispersion degreeof 1.65.

Synthetic Example 9 Synthesis of Polymer (h)

A round-bottom flask having a content volume of 100 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 2.18 g (9.78 mmol) of 1,4-dithiepane-2-yl=methacrylateobtained in Example 5, 2.31 g (9.78 mmol) of3-hydroxy-1-adamantyl=methacrylate, 42.0 g of 1,4-dioxane and 0.49 g(1.97 mmol) of 2,2′-azobis(2,4-dimethylvaleronitrile) under nitrogenatmosphere to carry out polymerization reaction at 60 to 65° C. for 4hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 37.5 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain2.68 g of a polymer (h) comprising a repetitive unit shown below. Thepolymer (h) thus obtained had Mw of 14,400 and a dispersion degree of1.59.

Synthetic Example 10 Synthesis of Polymer (i)

A round-bottom flask having a content volume of 100 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 2.09 g (9.35 mmol) of 1,4-dithiepane-2-yl=methacrylateobtained in Example 5, 1.48 g (6.25 mmol) of3-hydroxy-1-adamantyl=methacrylate, 2.08 g (9.35 mmol) of5-methacryloyloxy-2,6-norbornanecarbolactone, 50.0 g of 1,4-dioxane and1.24 g (5.0 mmol) of 2,2′-azobis(2,4-dimethylvaleronitrile) undernitrogen atmosphere to carry out polymerization reaction at 60 to 65° C.for 4 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 40.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 3.09 g of a polymer (i) comprising a repetitive unit shown below.The polymer (i) thus obtained had Mw of 14,000 and a dispersion degreeof 1.77.

Synthetic Example 11 Synthesis of Polymer (j)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Synthetic Example 9, except that in SyntheticExample 9, 2.34 g (9.78 mmol) of5,6-dimethyl-1,4-dithiane-2-yl=methacrylate obtained in Example 7 wasused in place of 2.18 g (9.78 mmol) of 1,4-dithiepane-2-yl=methacrylate.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 37.5 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain2.76 g of a polymer (j) comprising a repetitive unit shown below. Thepolymer (j) thus obtained had Mw of 15,800 and a dispersion degree of1.49.

Synthetic Example 12 Synthesis of Polymer (k)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Synthetic Example 10, except that in SyntheticExample 10, 2.23 g (9.35 mmol) of5,6-dimethyl-1,4-dithiane-2-yl=methacrylate obtained in Example 7 wasused in place of 2.09 g (9.35 mmol) of 1,4-dithiepane-2-yl=methacrylate.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 40.0 g of 1,4-dioxane, and thesolution prepared was dropwise added to methanol of the same mass asdescribed above while stirring. A precipitate produced was separated byfiltering and then washed with methanol of the same mass as describedabove, whereby a white precipitate was obtained. The above precipitatewas dried at 50° C. for 10 hours under reduced pressure (26.7 Pa) toobtain 2.69 g of a polymer (k) comprising a repetitive unit shown below.The polymer (k) thus obtained had Mw of 15,900 and a dispersion degreeof 1.68.

Comparative Synthetic Example 1 Synthesis of Polymer (A)

A round-bottom flask having a content volume of 200 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 10.0 g (42.3 mmol) of2-methyl-2-adamantyl=methacrylate, 10.0 g (42.7 mmol) of3-hydroxy-1-adamantyl=methacrylate, 80.0 g of propylene glycolmonomethyl ether and 1.40 g (8.53 mmol) of 2,2′-azobisisobutyronitrileunder nitrogen atmosphere to carry out polymerization reaction at 81 to87° C. for 2 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 100.0 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain13.2 g of a polymer (A) comprising a repetitive unit shown below. Thepolymer (A) thus obtained had Mw of 16,100 and a dispersion degree of1.68.

Comparative Synthetic Example 2 Synthesis of Polymer (B)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Comparative Synthetic Example 1, except thatin Comparative Synthetic Example 1, 7.39 g (42.7 mmol) oftetrahydropyran-2-yl=methacrylate was used in place of 10.0 g (42.3mmol) of 2-methyl-2-adamantyl=methacrylate.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 100.0 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain9.96 g of a polymer (B) comprising a repetitive unit shown below. Thepolymer (B) thus obtained had Mw of 13,200 and a dispersion degree of1.71.

Comparative Synthetic Example 3 Synthesis of Polymer (C)

A round-bottom flask having a content volume of 200 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 9.14 g (50.2 mmol) of1-methyl-1-cyclohexyl=methacrylate, 11.82 g (50.0 mmol) of3-hydroxy-1-adamantyl=methacrylate, 101.4 g of 1,4-dioxane and 1.24 g(7.55 mmol) of 2,2′-azobisisobutyronitrile under nitrogen atmosphere tocarry out polymerization reaction at 80 to 82° C. for 5 hours.

A reaction mixture obtained was dropwise added to a water-methanol mixedsolution (mass ratio water:methanol=1:3) of about 20 mass per mass ofthe reaction mixture at room temperature while stirring, and aprecipitate produced was separated by filtering. The above precipitatewas dissolved in 140.0 g of THF, and the solution prepared was dropwiseadded to the water-methanol mixed solution (mass ratiowater:methanol=1:3) of the same mass as described above while stirring.A precipitate produced was separated by filtering and then washed withthe water-methanol mixed solution (mass ratio water:methanol=1:3) of thesame mass as described above, whereby a white precipitate was obtained.The above precipitate was dried at 50° C. for 10 hours under reducedpressure (26.7 Pa) to obtain 11.8 g of a polymer (C) comprising arepetitive unit shown below. The polymer (C) thus obtained had Mw of12,600 and a dispersion degree of 1.83.

Comparative Synthetic Example 4 Synthesis of Polymer (D)

A round-bottom flask having a content volume of 100 mL equipped with anelectromagnetic stirring device, a reflux condenser and a thermometerwas charged with 4.39 g (18.7 mmol) of2-methacryloyloxy-2-methyladamantane, 2.95 g (12.5 mmol) of3-hydroxy-1-adamantyl-methacrylate, 3.18 g (18.7 mmol) ofα-methacryloyloxy-γ-butyrolactone, 35.4 g of methyl ethyl ketone and0.66 g (4.0 mmol) of 2,2′-azobisisobutyronitrile under nitrogenatmosphere to carry out polymerization reaction at 80° C. for 4 hours.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, whereby a white precipitate was obtained. The aboveprecipitate was separated by filtering and dried at 50° C. for 10 hoursunder reduced pressure (26.7 Pa) to obtain 6.06 g of a polymer (D)comprising a repetitive unit shown below. The polymer (D) thus obtainedhad Mw of 10,000 and a dispersion degree of 1.50.

Comparative Synthetic Example 5 Synthesis of Polymer (E)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Comparative Synthetic Example 4, except thatin Comparative Synthetic Example 4, 3.18 g (18.7 mmol) oftetrahydropyran-2-yl=methacrylate was used in place of 4.39 g (18.7mmol) of 2-methacryloyloxy-2-methyladamantane.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, whereby a white precipitate was obtained. The aboveprecipitate was separated by filtering and dried at 50° C. for 10 hoursunder reduced pressure (26.7 Pa) to obtain 5.82 g of a polymer (E)comprising a repetitive unit shown below. The polymer (E) thus obtainedhad Mw of 6,500 and a dispersion degree of 1.60.

Comparative Synthetic Example 6 Synthesis of Polymer (F)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Comparative Synthetic Example 4, except thatin Comparative Synthetic Example 4, 3.41 g (18.7 mmol) of1-methyl-1-cyclohexyl=methacrylate was used in place of 4.39 g (18.7mmol) of 2-methacryloyloxy-2-methyladamantane.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, whereby a white precipitate was obtained. The aboveprecipitate was separated by filtering and dried at 50° C. for 10 hoursunder reduced pressure (26.7 Pa) to obtain 5.69 g of a polymer (F)comprising a repetitive unit shown below. The polymer (F) thus obtainedhad Mw of 6,900 and a dispersion degree of 1.58.

Comparative Synthetic Example 7 Synthesis of Polymer (G)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Comparative Synthetic Example 1, except thatin Comparative Synthetic Example 1, 8.98 g (42.7 mmol) of1,3-dithiane-5-yl=methacrylate was used in place of 10.0 g (42.3 mmol)of 2-methyl-2-adamantyl=methacrylate.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, and a precipitate produced was separated by filtering. Theabove precipitate was dissolved in 100.0 g of THF, and the solutionprepared was dropwise added to methanol of the same mass as describedabove while stirring. A precipitate produced was separated by filteringand then washed with methanol of the same mass as described above,whereby a white precipitate was obtained. The above precipitate wasdried at 50° C. for 10 hours under reduced pressure (26.7 Pa) to obtain10.22 g of a polymer (G) comprising a repetitive unit shown below. Thepolymer (G) thus obtained had Mw of 15,200 and a dispersion degree of1.69.

Comparative Synthetic Example 8 Synthesis of Polymer (H)

Polymerization reaction was carried out in the same charge amounts onthe same conditions as in Comparative Synthetic Example 4, except thatin Comparative Synthetic Example 4, 3.93 g (18.7 mmol) of1,3-dithiane-5-yl=methacrylate was used in place of 4.39 g (18.7 mmol)of 2-methacryloyloxy-2-methyladamantane.

A reaction mixture obtained was dropwise added to methanol of about 20mass per mass of the reaction mixture at room temperature whilestirring, whereby a white precipitate was obtained. The aboveprecipitate was separated by filtering and dried at 50° C. for 10 hoursunder reduced pressure (26.7 Pa) to obtain 5.99 g of a polymer (H)comprising a repetitive unit shown below. The polymer (H) thus obtainedhad Mw of 12,800 and a dispersion degree of 1.65.

Examples 14 to 23 and Comparative Examples 1 to 8 Evaluation ofDissolution Characteristics in Developer by QCM Method

Used were 100 parts by mass of the polymer obtained in SyntheticExamples 3 to 12 or Comparative Synthetic Examples 1 to 8, 3 parts bymass of TPS-109 (trade name, component: triphenylsulfoniumnonafluoro-n-butanesulfonate, manufactured by Midori Kagaku Co., Ltd.)as a photoacid generator and as solvents, ethyl lactate when the polymer(b), (c), (d), (e), (h), (j), (A), (B), (C) and (G) were used and amixed solvent of propylene glycol monomethyl ether acetate/ethyllactate=1/1 (volume ratio) when the polymer other than above ones wereused, and the respective components were mixed to prepare photoresistcompositions in which a concentration of the polymer was 12% by mass.

The respective photoresist compositions thus obtained were filtratedthrough a filter (made of a tetrafluoroethylene resin (PTFE), porediameter: 0.2 μm), and then they were coated respectively by a spincoating method on a quartz substrate of a 1 inch size in which a goldelectrode was vacuum-deposited on a surface to form a photosensitivelayer having a thickness of 300 nm. The quartz substrate having aphotosensitive layer formed thereon was pre-baked at 110° C. for 90seconds on a hot plate and then exposed at an exposure dose of 100mJ/cm² with an ArF excimer laser (wavelength: 193 nm), and subsequentlyit was subjected to post-exposure baking at 110° C. for 90 seconds.

The quartz substrate described above was set in a quartz oscillatormicrobalance equipment “RQCM” (trade name; manufactured by Maxtek Corp.)and subjected to developing treatment by a tetramethylammonium hydroxideaqueous solution of 2.38% by mass for 120 seconds. A change in anoscillation frequency of the quartz substrate during the developingtreatment was monitored with the passage of time, and then a change inthe oscillation frequency was reduced to a change in the film thicknessto calculate the maximum swelling amount from a change in an increase ofthe film thickness and calculate the dissolution rate from a change in adecrease of the film thickness. The results thereof are shown in Table5.

TABLE 5 evaluation of dissolution characteristics in developer by QCMmethod Dissolution Maximum Polymer rate in swelling in photoresistdeveloping amount composition (nm/second) (nm) Example 14 (b) 1200 10Example 15 (c) 1240 10 Example 16 (d) 1240 8 Example 17 (e) 1300 8Example 18 (e) 1100 11 Example 19 (g) 1220 9 Example 20 (h) 1190 11Example 21 (i) 1290 9 Example 22 (j) 1240 11 Example 23 (k) 1340 9Comparative (A) 950 100 Example 1 Comparative (B) 1200 10 Example 2Comparative (C) 500 20 Example 3 Comparative (D) 600 40 Example 4Comparative (E) 1100 10 Example 5 Comparative (F) 530 10 Example 6Comparative (G) Not dissolved — Example 7 Comparative (H) Not dissolved— Example 8

Examples 24 to 33 and Comparative Examples 9 to 16 Evaluation ofExposure by Two-Beam Interference Method

Used were 100 parts by mass of the polymer obtained in SyntheticExamples 3 to 12 or Comparative Synthetic Examples 1 to 8, 3 parts bymass of TPS-109 (trade name, component: triphenylsulfoniumnonafluoro-n-butanesulfonate, manufactured by Midori Kagaku Co., Ltd.)as a photoacid generator and as solvents, ethyl lactate when the polymer(b), (c), (d), (e), (h), (j), (A), (B), (C) and (G) were used and amixed solvent of propylene glycol monomethyl ether acetate/ethyl lactate1/1 (volume ratio) when the polymer other than above ones were used, andthe respective components were mixed to prepare photoresist compositionsin which a concentration of the polymer was 12% by mass.

The respective photoresist compositions thus obtained were filtratedthrough a filter (made of a tetrafluoroethylene resin (PTFE), porediameter: 0.2 μm). A propylene glycol monomethyl ether acetate solutionof a cresol novolac resin (PS-6937, manufactured by Gunei ChemicalIndustry Co., Ltd.) having a concentration of 6% by mass was coated on asilicon wafer having a diameter of 10 cm by a spin coating method andbaked at 200° C. for 90 seconds on a hot plate to thereby form aanti-reflective coat (undercoat film), and the above filtrates werecoated respectively on the above silicon wafer by a spin coating methodand pre-baked at 130° C. for 90 seconds on a hot plate to thereby form aresist film having a film thickness of about 300 nm.

The above resist film was exposed with an ArF excimer laser having awavelength of 193 nm by a two-beam interference method. Subsequently, itwas subjected to post-exposure baking at 130° C. for 90 seconds and thento developing treatment for 60 seconds by a 2.38 mass %tetramethylammonium hydroxide aqueous solution to thereby form a lineand space pattern of 1:1. A piece obtained by cutting the wafersubjected to the development was observed under a scanning electronmicroscope (SEM) to observe a form of the pattern in an exposure dose inwhich the line and space having a line width of 100 nm was subjected toresolution by 1:1 and measure a change in the line width (hereinafterreferred to as LWR). The line width was detected in plural positions ina measuring monitor, and dispersion (3σ) in variation of the detectedpositions was set to an index for LWR. The results thereof are shown inTable 6.

TABLE 6 evaluation of exposure by two-beam interference method Polymerin photoresist composition LWR (nm) Pattern form Example 24 (b) 8.0 GoodExample 25 (c) 7.8 Good Example 26 (d) 7.2 Good Example 27 (e) 7.1 GoodExample 28 (f) 7.5 Good Example 29 (g) 7.3 Good Example 30 (h) 7.9 GoodExample 31 (i) 7.5 Good Example 32 (j) 8.0 Good Example 33 (k) 7.4 GoodComparative (A) 13.4 Good Example 9 Comparative (B) 8.1 Good Example 10Comparative (C) 10.1 Good Example 11 Comparative (D) 12.3 Good Example12 Comparative (E) 8.5 Good Example 13 Comparative (F) 9.3 Good Example14 Comparative (G) Unable to — Example 15 form pattern Comparative (H)Unable to — Example 16 form pattern

Examples 34 to 41 and Comparative Examples 17 to 21 Evaluation of HeatStability

The heat stabilities of the respective polymer obtained in SyntheticExamples 3 to 6 and 9 to 12 or Comparative Synthetic Examples 1 to 3, 7and 8 were confirmed by means of a micro heat weight measuring equipment“TGA-50” (trade name; manufactured by Shimadzu Corporation).

A sample amount of the polymer was set to about 5.0 mg, and the heatstability was measured at a nitrogen gas flow rate of 50 mL/minute and aheating rate of 10° C./minute in a range of 20 to 600° C. Thetemperature at which a reduction in the weight was initiated and thetemperature at which the weight was reduced by 5% based on the originalweight were read from a graph obtained. A reduction in the weight showsthat the polymer is decomposed by heat, and it can usually be understoodthat the higher the temperature at which a reduction in the weight isshown is, the more stable the polymer is to heat. The results thereofare shown in Table 7.

TABLE 7 evaluation of heat stability Decomposition Temperature Polymerinitiating in 5% weight in photoresist temperature reduction composition(° C.) (° C.) Example 34 (b) 170 203 Example 35 (c) 160 197 Example 36(d) 140 201 Example 37 (e) 170 200 Example 38 (h) 170 208 Example 39 (i)170 213 Example 40 (j) 160 200 Example 41 (k) 160 208 Comparative (A)190 227 Example 17 Comparative (B) 120 162 Example 18 Comparative (C)180 209 Example 19 Comparative (G) 170 192 Example 20 Comparative (H)170 195 Example 21

It can be found from the results shown in Table 5 to Table 7 that in thecase of the polymer containing the acrylic ester derivative (1) of thepresent invention in a constitutional unit, a dissolution rate in analkali developer used in a developing step when a pattern is formed onthe photoresist is very high as compared with the case of the polymercontaining no acrylic ester derivative (1) of the present invention in aconstitutional unit and that they have a very small maximum swellingamount in developing (refer to Examples 14 to 23 and ComparativeExamples 1 to 8) and are improved in LWR (refer to Examples 24 to 33 andComparative Examples 9 to 16). Further, they are excellent as well in aheat stability (refer to Examples 34 to 41 and Comparative Examples 17to 21), and therefore it can be found that they are useful as achemically amplified resist for producing semiconductor devices.

Reference Example 2 Preparation of Photoresist Composition b

The polymer (b) 100 parts by mass obtained in Synthetic Example 3,triphenylsulfonium nonafluoro-n-butanesulfonate 3.0 parts by mass as aphotoacid generator, N-(tert-butoxycarbonyl)pyrrolidine 0.27 part bymass as a basic compound and cyclohexanone 1962 parts by mass as asolvent were mixed to obtain a solution in which the respectivecomponents were homogeneously mixed. Then, the solution obtained abovewas filtrated through a membrane filter having a pore diameter of 0.2 μmto prepare a photoresist composition (b) (whole solid matterconcentration: about 5% by mass).

Measurement of Refractive Index:

The photoresist composition (b) prepared above was spin-coated on asilicon wafer by means of “CLEAN TRACK ACTS” manufactured by TokyoElectron Limited and pre-baked at 100° C. for 60 seconds to form aresist film having a film thickness of 120 nm.

A refractive index of the above resist film in a wavelength of 193 nmwas measured by means of a spectroscopic ellipsometer (“VUV-VASE”,manufactured by J. A. Woollam Co., Inc.). The results thereof are shownin Table 8.

Reference Examples 3 to 9 Preparation of Photoresist Compositions (d)and (f) to (k)

The experiment was carried out in the same manner as in ReferenceExample 2 to prepare respectively photoresist compositions (d) and (f)to (k) (whole solid matter concentration: about 5% by mass) and measurerefractive indices thereof in a wavelength of 193 nm, except that inReference Example 2, the polymer (d) and (f) to (k) obtained inSynthetic Examples 5 and 7 to 12 were used in place of the polymer (b).The results thereof are shown in Table 8.

Reference Examples 10 to 17 Preparation of Photoresist Compositions (A)to (H)

The experiment was carried out in the same manner as in ReferenceExample 2 to prepare respectively photoresist compositions (A) to (H)(whole solid matter concentration: about 5% by mass) and measurerefractive indices thereof in a wavelength of 193 nm, except that inReference Example 2, the polymer (A) to (H) obtained in ComparativeSynthetic Examples 1 to 8 were used in place of the polymer (b). Theresults thereof are shown in Table 8.

TABLE 8 measurement of refractive index Photoresist Refractivecomposition index Reference Example 2 (b) 1.77 Reference Example 3 (d)1.77 Reference Example 4 (f) 1.75 Reference Example 5 (g) 1.75 ReferenceExample 6 (h) 1.75 Reference Example 7 (i) 1.75 Reference Example 8 (j)1.74 Reference Example 9 (k) 1.74 Reference Example 10 (A) 1.70Reference Example 11 (B) 1.70 Reference Example 12 (C) 1.70 ReferenceExample 13 (D) 1.71 Reference Example 14 (E) 1.71 Reference Example 15(F) 1.71 Reference Example 16 (G) 1.75 Reference Example 17 (H) 1.75

Resist films generally used at present have a refractive index of 1.69to 1.71 in many cases, and such resist films do not involve the problemthat exposure light is less liable to be incident into a photoresistfilm when water (a refractive index: 1.44 in a wavelength of 193 nm) isused as an immersion liquid. However, when an immersion liquid of a nextgeneration (an immersion liquid having a refractive index of 1.71 ormore) having a larger refractive index than that of water is used in thefuture, exposure light is less liable to be sufficiently incident into aphotoresist film in the case of the above resist films generally used,and desired resist patterns are not obtained. However, according to thephotoresist composition (9) containing the polymer (8) containing theacrylic ester derivative (1) of the present invention in a structuralunit, exposure light is not reflected in an interface between theimmersion liquid and the photoresist film as well in a liquid immersionlithographic step in which the above immersion liquid of a nextgeneration is used in place of water, and it can sufficiently beincident into the photoresist film.

Reference Example 18 Characteristic Curve Measurement

A layer of anti-reflective coat (“ARC29A”, manufactured by BulwerScience Inc.) having a film thickness of 77 nm was formed on an 8 inchsilicon wafer used by means of “CLEAN TRACK ACT8” manufactured by TokyoElectron Limited. The photoresist composition (b) obtained in ReferenceExample 2 was spin-coated on the layer of anti-reflective coat formedabove by means of “CLEAN TRACK ACT8” (manufactured by Tokyo ElectronLimited.) and pre-baked at 100° C. for 60 seconds to form a resist filmhaving a film thickness of 120 nm.

The above resist film was exposed by means of an ArF excimer laserexposing equipment (“NSR S306C”, manufactured by Nikon Corporation,illumination condition: NA 0.78 sigma 0.90/0.52). This exposure wascarried out through quartz provided with no patterns.

Thereafter, the resist film was subjected to post-exposure baking at130° C. for 60 seconds and then developed by a tetramethylammoniumhydroxide aqueous solution of 2.38% by mass at 23° C. for 60 seconds.After developing, the film was washed with water and dried to obtain awafer for measuring a characteristic curve.

Then, the film thicknesses of the resist films obtained at therespective exposure doses were measured by means of an automatic filmthickness measuring equipment (“VM-2010”, manufactured by DainipponScreen Mfg. Co., Ltd.) to confirm correlation between the exposure dose(mJ/cm²) and the film thickness (angstrom (Å)). The results thereof areshown in FIG. 1.

Reference Example 19 Characteristic Curve Measurement

The measurement was carried out in the same manner, except that inReference Example 18, the photoresist composition (d) obtained inReference Example 3 was used in place of the photoresist composition(b). The results thereof are shown in FIG. 1.

It can be confirmed from FIG. 1 that a photoresist film formed by thephotoresist composition (9) containing the polymer (8) containing theacrylic ester derivative (1) in a structural unit is decreased in aresidual film thickness by increasing an exposure dose to make the wholephotoresist film soluble in a developer at a prescribed exposure dose,and it has been found that the exposure latitude (variation in a linewidth versus a change in an exposure dose) is good (refer to ReferenceExamples 18 and 19). Accordingly, a coating film formed by thephotoresist composition (9) containing the polymer (8) containing theacrylic ester derivative (1) in a structural unit can sufficiently besubjected to patterning for a photoresist film, and the contrast isexpected to be sufficiently obtained.

As shown above, the photoresist composition (9) containing the polymer(8) containing the acrylic ester derivative (1) of the present inventionin a structural unit makes it possible to form a photoresist film havinga high sensitivity, and the polymer (8) obtained by using the acrylicester derivative (1) of the present invention is useful as a chemicallyamplified resist for producing semiconductor devices.

INDUSTRIAL APPLICABILITY

The acrylic ester derivative (1) obtained in the present invention isuseful as a raw material for the polymer (8) added to the photoresistcomposition (9). Further, the alcohol (5) and the ester (6) eachobtained in the present invention are useful as a raw material for theabove acrylic ester derivative (1).

1. A process for producing an acrylic ester derivative, the processcomprising, in the following order: (I) reacting a dithiol of formula(2) with a base:

wherein in n, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰: 1) when n is 0, R⁵ and R⁸ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms; R⁶ and R⁷ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms or R⁶ and R⁷together form an alkylene group comprising 3 to 6 carbon atoms; or 2)when n is 1 or 2, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are each independently ahydrogen atom, a linear alkyl group comprising 1 to 6 carbon atoms, abranched alkyl group comprising 3 to 6 carbon atoms, or a cyclic alkylgroup comprising 3 to 6 carbon atoms, to obtain a reaction product; (II)reacting the reaction product with halide of formula (4):

wherein: R², R³, and R⁴ together satisfy any of: 1) R², R³ and R⁴ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms; 2) R² and R³together form an alkylene group comprising 3 to 6 carbon atoms, and R⁴is a hydrogen atom, a linear alkyl group comprising 1 to 6 carbon atoms,a branched alkyl group comprising 3 to 6 carbon atoms, or a cyclic alkylgroup comprising 3 to 6 carbon atoms; or 3) R² is a hydrogen atom, alinear alkyl group comprising 1 to 6 carbon atoms, a branched alkylgroup comprising 3 to 6 carbon atoms, or a cyclic alkyl group comprising3 to 6 carbon atoms, and R³ and R⁴ together form an alkylene groupcomprising 3 to 6 carbon atoms; R¹¹ is a linear alkyl group comprising 1to 3 carbon atoms or a branched alkyl group comprising 3 to 6 carbonatoms; X is a chlorine atom, a bromine atom, or an iodine atom; and R¹³is a linear alkyl group comprising 1 to 6 carbon atoms, a branched alkylgroup comprising 3 to 6 carbon atoms, or a cyclic alkyl group comprising3 to 6 carbon atoms, to obtain an ester of formula (6):

wherein n, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, and R¹³ are the sameas above; (III) hydrolyzing the ester of formula (6), to obtain analcohol of formula (5):

wherein n, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are the same asabove; and (IV) reacting the alcohol of formula (5), in the presence ofa basic substance, with a polymerizable group-introducing agent having aformula selected from the group consisting of:CH₂═CR¹COX¹;(CH₂═CR¹CO)₂O;CH₂═CR¹COOC(═O)R¹⁴; andCH₂═CR¹COOSO₂R¹⁵; wherein: R¹ is a hydrogen atom, methyl, ortrifluoromethyl; X¹ is a chlorine atom, a bromine atom, or an iodineatom; R¹⁴ is t-butyl or 2,4,6-trichlorophenyl; and R¹⁵ is methyl orp-tolyl, thereby obtaining an acrylic ester derivative of formula (1):

wherein n, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are the same asabove.
 2. The process of claim 1, wherein the base reacted with thedithiol is sodium hydride.
 3. A process for producing an acrylic esterderivative, the process comprising, in the following order: (I) reactinga base with dithiol of formula (2):

wherein in n, R⁵, R⁶, R⁷, R⁸, R⁹, and R₁₀: 1) when n is 0, R⁵ and R⁸ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms; R⁶ and R⁷ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms or R⁶ and R⁷together form an alkylene group comprising 3 to 6 carbon atoms; or 2)when n is 1 or 2, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are each independently ahydrogen atom, a linear alkyl group comprising 1 to 6 carbon atoms, abranched alkyl group comprising 3 to 6 carbon atoms, or a cyclic alkylgroup comprising 3 to 6 carbon atoms, to obtain a reaction product; (II)reacting the reaction product with a halide of formula (4):

wherein: R², R³, and R⁴ together satisfy any of: 1) R², R³ and R⁴ areeach independently a hydrogen atom, a linear alkyl group comprising 1 to6 carbon atoms, a branched alkyl group comprising 3 to 6 carbon atoms,or a cyclic alkyl group comprising 3 to 6 carbon atoms; 2) R² and R³together form an alkylene group comprising 3 to 6 carbon atoms, and R⁴is a hydrogen atom, a linear alkyl group comprising 1 to 6 carbon atoms,a branched alkyl group comprising 3 to 6 carbon atoms, or a cyclic alkylgroup comprising 3 to 6 carbon atoms; or 3) R² is a hydrogen atom, alinear alkyl group comprising 1 to 6 carbon atoms, a branched alkylgroup comprising 3 to 6 carbon atoms, or a cyclic alkyl group comprising3 to 6 carbon atoms, and R³ and R⁴ together form an alkylene groupcomprising 3 to 6 carbon atoms; and R¹¹ is a linear alkyl groupcomprising 1 to 3 carbon atoms or a branched alkyl group comprising 3 to6 carbon atoms; X is a chlorine atom, a bromine atom, or an iodine atom;and R¹³ is a linear alkyl group comprising 1 to 6 carbon atoms, abranched alkyl group comprising 3 to 6 carbon atoms, or a cyclic alkylgroup comprising 3 to 6 carbon atoms, to obtain alcohol of formula (5):

wherein n, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are the same asabove; and (III) reacting alcohol of formula (5), in the presence of abasic substance, with a polymerizable group-introducing agent having aformula selected from the group consisting of:CH₂═CR¹COX¹;(CH₂═CR¹CO)₂O;CH₂═CR¹COOC(═O)R¹⁴; andCH₂═CR¹COOSO₂R¹⁵; wherein: R¹ is a hydrogen atom, methyl, ortrifluoromethyl; X¹ is a chlorine atom, a bromine atom, or an iodineatom; R¹⁴ is t-butyl or 2,4,6-trichlorophenyl; and R¹⁵ is methyl orp-tolyl, thereby obtaining an acrylic ester derivative of formula (1):

wherein n, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are the same asabove.
 4. The process of claim 3, wherein the base reacted with thedithiol is sodium hydride.